diff --git a/src/tck/CMakeLists.txt b/src/tck/CMakeLists.txt
index 19d043049..0aa57f769 100644
--- a/src/tck/CMakeLists.txt
+++ b/src/tck/CMakeLists.txt
@@ -10,6 +10,7 @@ add_executable(${TCK_SERVER_NAME}
         src/key/KeyService.cc
         src/sdk/SdkClient.cc
         src/token/TokenService.cc
+        src/topic/TopicService.cc
         src/main.cc
         src/TckServer.cc)
 
diff --git a/src/tck/include/topic/TopicService.h b/src/tck/include/topic/TopicService.h
new file mode 100644
index 000000000..38f3e2e15
--- /dev/null
+++ b/src/tck/include/topic/TopicService.h
@@ -0,0 +1,51 @@
+// SPDX-License-Identifier: Apache-2.0
+#ifndef HIERO_TCK_CPP_TOPIC_SERVICE_H_
+#define HIERO_TCK_CPP_TOPIC_SERVICE_H_
+
+#include <nlohmann/json_fwd.hpp>
+
+namespace Hiero::TCK::TopicService
+{
+/**
+ * Forward declarations.
+ */
+struct CreateTopicParams;
+struct DeleteTopicParams;
+struct GetTopicInfoQueryParams;
+struct TopicMessageSubmitParams;
+
+/**
+ * Create a topic.
+ *
+ * @param params The parameters to use to create a topic.
+ * @return A JSON response containing the status of the topic creation and the new topic's ID.
+ */
+nlohmann::json createTopic(const CreateTopicParams& params);
+
+/**
+ * Delete a topic
+ *
+ * @param params The parameters to use to delete a topic.
+ * @return A json response containing the status of the deletion of the topic.
+ */
+nlohmann::json deleteTopic(const DeleteTopicParams& params);
+
+/**
+ * Get topic info.
+ *
+ * @param params The parameters to use to get info of a topic.
+ * @return A JSON response containing the status of the topic info.
+ */
+nlohmann::json getTopicInfo(const GetTopicInfoQueryParams& params);
+
+/**
+ * Submit a topic message.
+ *
+ * @param params The parameters to use to submit a topic message.
+ * @return A JSON response containing the status of the submission of the topic message.
+ */
+nlohmann::json submitTopicMessage(const TopicMessageSubmitParams& params);
+
+} // namespace Hiero::TCK::TopicService
+
+#endif // HIERO_TCK_CPP_TOPIC_SERVICE_H_
diff --git a/src/tck/include/topic/params/CreateTopicParams.h b/src/tck/include/topic/params/CreateTopicParams.h
new file mode 100644
index 000000000..fb0227fcf
--- /dev/null
+++ b/src/tck/include/topic/params/CreateTopicParams.h
@@ -0,0 +1,116 @@
+// SPDX-License-Identifier: Apache-2.0
+#ifndef HIERO_TCK_CPP_CREATE_TOPIC_PARAMS_H_
+#define HIERO_TCK_CPP_CREATE_TOPIC_PARAMS_H_
+
+#include "common/CommonTransactionParams.h"
+#include "nlohmann/json.hpp"
+
+#include "token/CustomFeeSerializer.h"
+
+#include "json/JsonUtils.h"
+#include <optional>
+#include <string>
+#include <vector>
+
+namespace Hiero::TCK::TopicService
+{
+/**
+ * Struct to hold the arguments for a `createTopic` JSON-RPC method call.
+ */
+struct CreateTopicParams
+{
+  /**
+   * Short publicly visible memo about the topic. No guarantee of uniqueness. (UTF-8 encoding max 100 bytes)
+   */
+  std::optional<std::string> mMemo;
+
+  /**
+   * Access control for update/delete of the topic. DER-encoded hex string representation for private or public keys.
+   * Keylists and threshold keys are the hex of the serialized protobuf bytes.
+   */
+  std::optional<std::string> mAdminKey;
+
+  /**
+   * Access control for submit message. DER-encoded hex string representation for private or public keys. Keylists and
+   * threshold keys are the hex of the serialized protobuf bytes.
+   */
+  std::optional<std::string> mSubmitKey;
+
+  /**
+   * The amount of time to attempt to extend the topic's lifetime by automatically at the topic's expirationTime. Units
+   * of seconds. Min: 6999999 (≈30 days), Max: 8000001 (≈92 days)
+   */
+  std::optional<std::string> mAutoRenewPeriod;
+
+  /**
+   * Optional account to be used at the topic's expirationTime to extend the life of the topic. Must sign transaction if
+   * specified.
+   */
+  std::optional<std::string> mAutoRenewAccount;
+
+  /**
+   * A key that controls updates and deletions of topic fees. DER-encoded hex string representation for private or
+   * public keys. Keylists and threshold keys are the hex of the serialized protobuf bytes.
+   */
+  std::optional<std::string> mFeeScheduleKey;
+
+  /**
+   * A list of keys that, if used to sign a message submission, allow the sender to bypass fees. DER-encoded hex string
+   * representation for private or public keys.
+   */
+  std::optional<std::vector<std::string>> mFeeExemptKeys;
+
+  /**
+   * A fee structure applied to message submissions for revenue generation.
+   */
+  std::optional<std::vector<std::shared_ptr<CustomFee>>> mCustomFees;
+
+  /**
+   * Any parameters common to all transaction types.
+   */
+  std::optional<CommonTransactionParams> mCommonTxParams;
+};
+
+} // namespace Hiero::TCK::TopicService
+
+namespace nlohmann
+{
+/**
+ * JSON serializer template specialization required to convert CreateTopicParams arguments properly.
+ */
+template<>
+struct [[maybe_unused]] adl_serializer<Hiero::TCK::TopicService::CreateTopicParams>
+{
+  /**
+   * Convert a Json Object to a CreateTopicParams
+   *
+   * @param jsonFrom The json object which will fill the CreateTopicParams.
+   * @param params The CreateTopicParam to fill the json object.
+   */
+  static void from_json(const json& jsonFrom, Hiero::TCK::TopicService::CreateTopicParams& params)
+  {
+    params.mMemo = Hiero::TCK::getOptionalJsonParameter<std::string>(jsonFrom, "memo");
+
+    params.mAdminKey = Hiero::TCK::getOptionalJsonParameter<std::string>(jsonFrom, "adminKey");
+
+    params.mSubmitKey = Hiero::TCK::getOptionalJsonParameter<std::string>(jsonFrom, "submitKey");
+
+    params.mAutoRenewPeriod = Hiero::TCK::getOptionalJsonParameter<std::string>(jsonFrom, "autoRenewPeriod");
+
+    params.mAutoRenewAccount = Hiero::TCK::getOptionalJsonParameter<std::string>(jsonFrom, "autoRenewAccount");
+
+    params.mFeeScheduleKey = Hiero::TCK::getOptionalJsonParameter<std::string>(jsonFrom, "feeScheduleKey");
+
+    params.mFeeExemptKeys = Hiero::TCK::getOptionalJsonParameter<std::vector<std::string>>(jsonFrom, "feeExemptKeys");
+
+    params.mCustomFees =
+      Hiero::TCK::getOptionalJsonParameter<std::vector<std::shared_ptr<Hiero::CustomFee>>>(jsonFrom, "customFees");
+
+    params.mCommonTxParams =
+      Hiero::TCK::getOptionalJsonParameter<Hiero::TCK::CommonTransactionParams>(jsonFrom, "commonTransactionParams");
+  }
+};
+
+} // namespace nlohmann
+
+#endif // HIERO_TCK_CPP_CREATE_TOPIC_PARAMS_H_
diff --git a/src/tck/include/topic/params/DeleteTopicParams.h b/src/tck/include/topic/params/DeleteTopicParams.h
new file mode 100644
index 000000000..8a5c52a09
--- /dev/null
+++ b/src/tck/include/topic/params/DeleteTopicParams.h
@@ -0,0 +1,57 @@
+// SPDX-License-Identifier: Apache-2.0
+#ifndef HIERO_TCK_CPP_DELETE_TOPIC_PARAMS_H_
+#define HIERO_TCK_CPP_DELETE_TOPIC_PARAMS_H_
+
+#include "common/CommonTransactionParams.h"
+#include "nlohmann/json.hpp"
+
+#include "json/JsonUtils.h"
+#include <optional>
+#include <string>
+
+namespace Hiero::TCK::TopicService
+{
+/**
+ * Struct to hold the arguments for a `deleteTopic` Json-RPC method call.
+ */
+struct DeleteTopicParams
+{
+  /**
+   * The ID of the topic to delete.
+   */
+  std::optional<std::string> mTopicId;
+
+  /**
+   * Any parameters common to all transaction types.
+   */
+  std::optional<CommonTransactionParams> mCommonTxParams;
+};
+
+} // namespace Hiero::TCK::TopicService
+
+namespace nlohmann
+{
+/**
+ * JSON serializer template specialisation required to convert DeleteTopicParams argument properly.
+ */
+template<>
+struct [[maybe_unused]] adl_serializer<Hiero::TCK::TopicService::DeleteTopicParams>
+{
+  /**
+   * Convert a JSON object to a DeleteTopicParams.
+   *
+   * @param jsonFrom The JSON object with which to fill the DeleteTopicParams.
+   * @param params   The DeleteTopicParams to fill with the JSON object.
+   */
+  static void from_json(const json& jsonFrom, Hiero::TCK::TopicService::DeleteTopicParams& params)
+  {
+    params.mTopicId = Hiero::TCK::getOptionalJsonParameter<std::string>(jsonFrom, "topicId");
+
+    params.mCommonTxParams =
+      Hiero::TCK::getOptionalJsonParameter<Hiero::TCK::CommonTransactionParams>(jsonFrom, "commonTransactionParams");
+  }
+};
+
+} // namespace nlohmann
+
+#endif // HIERO_TCK_CPP_DELETE_TOPIC_PARAMS_H_
diff --git a/src/tck/include/topic/params/GetTopicInfoQueryParams.h b/src/tck/include/topic/params/GetTopicInfoQueryParams.h
new file mode 100644
index 000000000..ea3ade739
--- /dev/null
+++ b/src/tck/include/topic/params/GetTopicInfoQueryParams.h
@@ -0,0 +1,62 @@
+// SPDX-License-Identifier: Apache-2.0
+#ifndef HIERO_TCK_CPP_GET_TOPIC_INFO_QUERY_PARAMS_H_
+#define HIERO_TCK_CPP_GET_TOPIC_INFO_QUERY_PARAMS_H_
+
+#include "nlohmann/json.hpp"
+
+#include "json/JsonUtils.h"
+#include <optional>
+#include <string>
+
+namespace Hiero::TCK::TopicService
+{
+/**
+ * Struct to hold the arguments for a `getTopicInfo` Json-RPC method call
+ */
+struct GetTopicInfoQueryParams
+{
+  /**
+   * The ID of the topic to query.
+   */
+  std::optional<std::string> mTopicId;
+
+  /**
+   * Explicit payment amount for the query in tinybars.
+   */
+  std::optional<std::string> mQueryPayment;
+
+  /**
+   * Maximum payment amount for the query in tinybars.
+   */
+  std::optional<std::string> mMaxQueryPayment;
+};
+
+} // namespace Hiero::TCK::TopicService
+
+namespace nlohmann
+{
+/**
+ * JSON serializer template specialisation required to convert GetTopicInfoQueryParams arguments properly.
+ */
+template<>
+struct [[maybe_unused]] adl_serializer<Hiero::TCK::TopicService::GetTopicInfoQueryParams>
+{
+  /**
+   * Convert a Json Object to a GetTopicInfoQueryParams
+   *
+   * @param jsonFrom The json object which will fill the GetTopicInfoQueryParams.
+   * @param params The GetTopicInfoQueryParams to fill the json object.
+   */
+  static void from_json(const json& jsonFrom, Hiero::TCK::TopicService::GetTopicInfoQueryParams& params)
+  {
+    params.mTopicId = Hiero::TCK::getOptionalJsonParameter<std::string>(jsonFrom, "topicId");
+
+    params.mQueryPayment = Hiero::TCK::getOptionalJsonParameter<std::string>(jsonFrom, "queryPayment");
+
+    params.mMaxQueryPayment = Hiero::TCK::getOptionalJsonParameter<std::string>(jsonFrom, "maxQueryPayment");
+  }
+};
+
+} // namespace nlohmann
+
+#endif // HIERO_TCK_CPP_GET_TOPIC_INFO_QUERY_PARAMS_H_
diff --git a/src/tck/include/topic/params/TopicMessageSubmitParams.h b/src/tck/include/topic/params/TopicMessageSubmitParams.h
new file mode 100644
index 000000000..5422e8688
--- /dev/null
+++ b/src/tck/include/topic/params/TopicMessageSubmitParams.h
@@ -0,0 +1,71 @@
+// SPDX-License-Identifier: Apache-2.0
+#ifndef HIERO_TCK_CPP_TOPIC_MESSAGE_SUBMIT_PARAMS_H_
+#define HIERO_TCK_CPP_TOPIC_MESSAGE_SUBMIT_PARAMS_H_
+
+#include "common/CommonTransactionParams.h"
+#include "nlohmann/json.hpp"
+
+#include "json/JsonUtils.h"
+#include <optional>
+#include <string>
+
+namespace Hiero::TCK::TopicService
+{
+/**
+ * Struct to hold the arguments for a `submitTopicMessage` JSON-RPC method call
+ */
+struct TopicMessageSubmitParams
+{
+  /**
+   * The ID of the topic to submit the message to.
+   */
+  std::optional<std::string> mTopicId;
+
+  /**
+   * The message content to submit. UTF-8 encoding. Will be automatically chunked if the message exceeds the chunk size.
+   */
+  std::optional<std::string> mMessage;
+
+  /**
+   * The maximum number of chunks the message can be split into. Default: 20. Used when message size exceeds chunk size.
+   */
+  std::optional<int> mMaxChunks;
+
+  /**
+   * Any parameters common to all transaction types.
+   */
+  std::optional<CommonTransactionParams> mCommonTxParams;
+};
+
+} // namespace Hiero::TCK::TopicService
+
+namespace nlohmann
+{
+/**
+ * Json serializer template specialisation required to convert TopicMessageSubmitParams argument properly
+ */
+template<>
+struct [[maybe_unused]] adl_serializer<Hiero::TCK::TopicService::TopicMessageSubmitParams>
+{
+  /**
+   * Convert a Json Object to a TopicMessageSubmitParams
+   *
+   * @param jsonFrom The JSON object with which to fill the TopicMessageSubmitParams
+   * @param params the TopicMessageSubmitParams to fill with the JSON object.
+   */
+  static void from_json(const json& jsonFrom, Hiero::TCK::TopicService::TopicMessageSubmitParams& params)
+  {
+    params.mTopicId = Hiero::TCK::getOptionalJsonParameter<std::string>(jsonFrom, "topicId");
+
+    params.mMessage = Hiero::TCK::getOptionalJsonParameter<std::string>(jsonFrom, "message");
+
+    params.mMaxChunks = Hiero::TCK::getOptionalJsonParameter<int>(jsonFrom, "maxChunks");
+
+    params.mCommonTxParams =
+      Hiero::TCK::getOptionalJsonParameter<Hiero::TCK::CommonTransactionParams>(jsonFrom, "commonTransactionParams");
+  }
+};
+
+} // namespace nlohmann
+
+#endif // HIERO_TCK_CPP_TOPIC_MESSAGE_SUBMIT_PARAMS_H_
diff --git a/src/tck/src/TckServer.cc b/src/tck/src/TckServer.cc
index b66af7e02..1493cdc08 100644
--- a/src/tck/src/TckServer.cc
+++ b/src/tck/src/TckServer.cc
@@ -44,6 +44,11 @@
 #include "token/params/UpdateTokenFeeScheduleParams.h"
 #include "token/params/UpdateTokenParams.h"
 #include "token/params/WipeTokenParams.h"
+#include "topic/TopicService.h"
+#include "topic/params/CreateTopicParams.h"
+#include "topic/params/DeleteTopicParams.h"
+#include "topic/params/GetTopicInfoQueryParams.h"
+#include "topic/params/TopicMessageSubmitParams.h"
 #include "json/JsonUtils.h"
 
 namespace Hiero::TCK
@@ -97,6 +102,12 @@ TckServer::TckServer(int port)
   mJsonRpcParser.addMethod("updateTokenFeeSchedule", getHandle(TokenService::updateTokenFeeSchedule));
   mJsonRpcParser.addMethod("wipeToken", getHandle(TokenService::wipeToken));
 
+  // Topic Service
+  mJsonRpcParser.addMethod("createTopic", getHandle(TopicService::createTopic));
+  mJsonRpcParser.addMethod("deleteTopic", getHandle(TopicService::deleteTopic));
+  mJsonRpcParser.addMethod("getTopicInfo", getHandle(TopicService::getTopicInfo));
+  mJsonRpcParser.addMethod("submitTopicMessage", getHandle(TopicService::submitTopicMessage));
+
   // Add the FileService functions.
   mJsonRpcParser.addMethod("appendFile", getHandle(FileService::appendFile));
   mJsonRpcParser.addMethod("createFile", getHandle(FileService::createFile));
@@ -225,5 +236,13 @@ template TckServer::MethodHandle TckServer::getHandle<FileService::GetFileInfoPa
   nlohmann::json (*method)(const FileService::GetFileInfoParams&));
 template TckServer::MethodHandle TckServer::getHandle<FileService::UpdateFileParams>(
   nlohmann::json (*method)(const FileService::UpdateFileParams&));
+template TckServer::MethodHandle TckServer::getHandle<TopicService::CreateTopicParams>(
+  nlohmann::json (*method)(const TopicService::CreateTopicParams&));
+template TckServer::MethodHandle TckServer::getHandle<TopicService::DeleteTopicParams>(
+  nlohmann::json (*method)(const TopicService::DeleteTopicParams&));
+template TckServer::MethodHandle TckServer::getHandle<TopicService::GetTopicInfoQueryParams>(
+  nlohmann::json (*method)(const TopicService::GetTopicInfoQueryParams&));
+template TckServer::MethodHandle TckServer::getHandle<TopicService::TopicMessageSubmitParams>(
+  nlohmann::json (*method)(const TopicService::TopicMessageSubmitParams&));
 
 } // namespace Hiero::TCK
diff --git a/src/tck/src/topic/TopicService.cc b/src/tck/src/topic/TopicService.cc
new file mode 100644
index 000000000..c6b3b2b76
--- /dev/null
+++ b/src/tck/src/topic/TopicService.cc
@@ -0,0 +1,246 @@
+// SPDX-License-Identifier: Apache-2.0
+#include "topic/TopicService.h"
+#include "common/CommonTransactionParams.h"
+#include "key/KeyService.h"
+#include "sdk/SdkClient.h"
+#include "token/CustomFeeSerializer.h"
+#include "topic/params/CreateTopicParams.h"
+#include "topic/params/DeleteTopicParams.h"
+#include "topic/params/GetTopicInfoQueryParams.h"
+#include "topic/params/TopicMessageSubmitParams.h"
+#include "json/JsonErrorType.h"
+#include "json/JsonRpcException.h"
+
+#include <AccountId.h>
+#include <CustomFixedFee.h>
+#include <Key.h>
+#include <TopicCreateTransaction.h>
+#include <TopicDeleteTransaction.h>
+#include <TopicId.h>
+#include <TopicInfo.h>
+#include <TopicInfoQuery.h>
+#include <TopicMessageSubmitTransaction.h>
+#include <TransactionReceipt.h>
+#include <TransactionResponse.h>
+#include <impl/EntityIdHelper.h>
+#include <impl/HexConverter.h>
+
+#include <algorithm>
+#include <chrono>
+#include <cstdint>
+#include <memory>
+#include <nlohmann/json.hpp>
+#include <string>
+#include <vector>
+
+namespace Hiero::TCK::TopicService
+{
+//-----
+nlohmann::json createTopic(const CreateTopicParams& params)
+{
+  TopicCreateTransaction topicCreateTransaction;
+  topicCreateTransaction.setGrpcDeadline(SdkClient::DEFAULT_TCK_REQUEST_TIMEOUT);
+
+  if (params.mMemo.has_value())
+  {
+    topicCreateTransaction.setMemo(params.mMemo.value());
+  }
+
+  if (params.mAdminKey.has_value())
+  {
+    topicCreateTransaction.setAdminKey(KeyService::getHieroKey(params.mAdminKey.value()));
+  }
+
+  if (params.mSubmitKey.has_value())
+  {
+    topicCreateTransaction.setSubmitKey(KeyService::getHieroKey(params.mSubmitKey.value()));
+  }
+
+  if (params.mAutoRenewPeriod.has_value())
+  {
+    topicCreateTransaction.setAutoRenewPeriod(
+      std::chrono::seconds(Hiero::internal::EntityIdHelper::getNum<int64_t>(params.mAutoRenewPeriod.value())));
+  }
+
+  if (params.mAutoRenewAccount.has_value())
+  {
+    topicCreateTransaction.setAutoRenewAccountId(AccountId::fromString(params.mAutoRenewAccount.value()));
+  }
+
+  if (params.mFeeScheduleKey.has_value())
+  {
+    topicCreateTransaction.setFeeScheduleKey(KeyService::getHieroKey(params.mFeeScheduleKey.value()));
+  }
+
+  if (params.mFeeExemptKeys.has_value())
+  {
+    std::vector<std::shared_ptr<Key>> feeExemptKeys;
+    for (const auto& keyStr : params.mFeeExemptKeys.value())
+    {
+      feeExemptKeys.push_back(KeyService::getHieroKey(keyStr));
+    }
+    topicCreateTransaction.setFeeExemptKeys(feeExemptKeys);
+  }
+
+  if (params.mCustomFees.has_value())
+  {
+    std::vector<CustomFixedFee> fixedFees;
+    for (const auto& fee : params.mCustomFees.value())
+    {
+      if (CustomFixedFee* feePtr = dynamic_cast<CustomFixedFee*>(fee.get()))
+      {
+        fixedFees.push_back(*feePtr);
+      }
+    }
+    topicCreateTransaction.setCustomFixedFees(fixedFees);
+  }
+
+  if (params.mCommonTxParams.has_value())
+  {
+    params.mCommonTxParams->fillOutTransaction(topicCreateTransaction, SdkClient::getClient());
+  }
+
+  const TransactionReceipt txReceipt =
+    topicCreateTransaction.execute(SdkClient::getClient()).getReceipt(SdkClient::getClient());
+
+  return {
+    {"topicId", txReceipt.mTopicId.value().toString()},
+    { "status", gStatusToString.at(txReceipt.mStatus)}
+  };
+}
+
+//-----
+nlohmann::json deleteTopic(const DeleteTopicParams& params)
+{
+  TopicDeleteTransaction topicDeleteTransaction;
+  topicDeleteTransaction.setGrpcDeadline(SdkClient::DEFAULT_TCK_REQUEST_TIMEOUT);
+
+  if (params.mTopicId.has_value())
+  {
+    topicDeleteTransaction.setTopicId(TopicId::fromString(params.mTopicId.value()));
+  }
+
+  if (params.mCommonTxParams.has_value())
+  {
+    params.mCommonTxParams->fillOutTransaction(topicDeleteTransaction, SdkClient::getClient());
+  }
+
+  return {
+    {"status",
+     gStatusToString.at(
+        topicDeleteTransaction.execute(SdkClient::getClient()).getReceipt(SdkClient::getClient()).mStatus)},
+  };
+}
+
+//-----
+nlohmann::json getTopicInfo(const GetTopicInfoQueryParams& params)
+{
+  TopicInfoQuery getTopicInfoQuery;
+  getTopicInfoQuery.setGrpcDeadline(SdkClient::DEFAULT_TCK_REQUEST_TIMEOUT);
+
+  if (params.mTopicId.has_value())
+  {
+    getTopicInfoQuery.setTopicId(TopicId::fromString(params.mTopicId.value()));
+  }
+
+  if (params.mQueryPayment.has_value())
+  {
+    getTopicInfoQuery.setQueryPayment(Hbar::fromTinybars(std::stoll(params.mQueryPayment.value())));
+  }
+
+  if (params.mMaxQueryPayment.has_value())
+  {
+    getTopicInfoQuery.setMaxQueryPayment(Hbar::fromTinybars(std::stoll(params.mMaxQueryPayment.value())));
+  }
+
+  const TopicInfo info = getTopicInfoQuery.execute(SdkClient::getClient());
+
+  nlohmann::json response;
+
+  response["topicId"] = info.mTopicId.toString();
+  response["topicMemo"] = info.mMemo;
+  response["sequenceNumber"] = std::to_string(info.mSequenceNumber);
+
+  auto expirySeconds =
+    std::chrono::duration_cast<std::chrono::seconds>(info.mExpirationTime.time_since_epoch()).count();
+  response["expirationTime"] = std::to_string(expirySeconds);
+
+  if (info.mAutoRenewPeriod.has_value())
+  {
+    response["autoRenewPeriod"] =
+      std::to_string(std::chrono::duration_cast<std::chrono::seconds>(info.mAutoRenewPeriod.value()).count());
+  }
+
+  if (info.mAutoRenewAccountId.has_value())
+  {
+    response["autoRenewAccountId"] = info.mAutoRenewAccountId.value().toString();
+  }
+
+  if (info.mAdminKey)
+  {
+    response["adminKey"] = internal::HexConverter::bytesToHex(info.mAdminKey->toBytes());
+  }
+
+  if (info.mSubmitKey)
+  {
+    response["submitKey"] = internal::HexConverter::bytesToHex(info.mSubmitKey->toBytes());
+  }
+
+  if (info.mFeeScheduleKey)
+  {
+    response["feeScheduleKey"] = internal::HexConverter::bytesToHex(info.mFeeScheduleKey->toBytes());
+  }
+
+  response["feeExemptKeys"] = nlohmann::json::array();
+  for (const auto& key : info.mFeeExemptKeys)
+  {
+    response["feeExemptKeys"].push_back(internal::HexConverter::bytesToHex(key->toBytes()));
+  }
+
+  response["customFees"] = nlohmann::json::array();
+  for (const auto& fee : info.mCustomFixedFees)
+  {
+    std::shared_ptr<CustomFee> feePtr = std::make_shared<CustomFixedFee>(fee);
+    response["customFees"].push_back(feePtr);
+  }
+
+  response["ledgerId"] = info.mLedgerId.toString();
+
+  return response;
+}
+
+//-----
+nlohmann::json submitTopicMessage(const TopicMessageSubmitParams& params)
+{
+  TopicMessageSubmitTransaction topicMessageSubmitTransaction;
+
+  topicMessageSubmitTransaction.setGrpcDeadline(SdkClient::DEFAULT_TCK_REQUEST_TIMEOUT);
+
+  if (params.mTopicId.has_value())
+  {
+    topicMessageSubmitTransaction.setTopicId(TopicId::fromString(params.mTopicId.value()));
+  }
+
+  if (params.mMessage.has_value())
+  {
+    topicMessageSubmitTransaction.setMessage(params.mMessage.value());
+  }
+
+  if (params.mMaxChunks.has_value())
+  {
+    topicMessageSubmitTransaction.setMaxChunks(static_cast<int>(params.mMaxChunks.value()));
+  }
+
+  if (params.mCommonTxParams.has_value())
+  {
+    params.mCommonTxParams->fillOutTransaction(topicMessageSubmitTransaction, SdkClient::getClient());
+  }
+
+  return {
+    {"status",
+     gStatusToString.at(
+        topicMessageSubmitTransaction.execute(SdkClient::getClient()).getReceipt(SdkClient::getClient()).mStatus)}
+  };
+}
+
+} // namespace Hiero::TCK::TopicService