diff --git a/matminer/featurizers/composition/tests/test_composite.py b/matminer/featurizers/composition/tests/test_composite.py
index ddb45edcf..c86b4bea0 100644
--- a/matminer/featurizers/composition/tests/test_composite.py
+++ b/matminer/featurizers/composition/tests/test_composite.py
@@ -1,5 +1,7 @@
 import math
 import unittest
+import pandas as pd
+from pymatgen.core import Composition
 
 from matminer.featurizers.composition.composite import ElementProperty, Meredig
 from matminer.featurizers.composition.tests.base import CompositionFeaturesTest
@@ -23,6 +25,20 @@ def test_elem_deml(self):
         self.assertAlmostEqual(df_elem_deml["DemlData mean atom_num"][0], 15.2)
         self.assertAlmostEqual(df_elem_deml["DemlData std_dev atom_num"][0], 12.7279, 4)
 
+        df_for_RE = pd.DataFrame(
+            {
+                "composition": [
+                    Composition("Mg99.21Zn0.18Mn0.02Ce0.48Si0.01La0.1"),
+                ]
+            }
+        )
+        df_elem_deml_for_RE = ElementProperty.from_preset("deml").featurize_dataframe(df_for_RE, col_id="composition")
+        self.assertAlmostEqual(df_elem_deml_for_RE["DemlData minimum heat_cap"][0], 19.789)
+        self.assertAlmostEqual(df_elem_deml_for_RE["DemlData maximum heat_cap"][0], 27.11)
+        self.assertAlmostEqual(df_elem_deml_for_RE["DemlData range heat_cap"][0], 7.32099999999999)
+        self.assertAlmostEqual(df_elem_deml_for_RE["DemlData mean heat_cap"][0], 24.8819017999999)
+        self.assertAlmostEqual(df_elem_deml_for_RE["DemlData std_dev heat_cap"][0], 1.35708660591194)
+
     def test_elem_matminer(self):
         df_elem = ElementProperty.from_preset("matminer").featurize_dataframe(self.df, col_id="composition")
         self.assertAlmostEqual(df_elem["PymatgenData minimum melting_point"][0], 54.8, 1)
diff --git a/matminer/utils/data_files/deml_elementdata.py b/matminer/utils/data_files/deml_elementdata.py
index 151334198..d2bd5a05a 100644
--- a/matminer/utils/data_files/deml_elementdata.py
+++ b/matminer/utils/data_files/deml_elementdata.py
@@ -1036,6 +1036,8 @@
 # from CRC handbook: 25C and thermo stable standard state, 1 bar
 # units: J/mol.K
 heat_cap = {
+    "H": 28.836,
+    "He": 20.786,
     "Li": 24.86,
     "Be": 16.443,
     "B": 11.087,
@@ -1043,6 +1045,7 @@
     "N": 29.124,
     "O": 29.378,
     "F": 31.304,
+    "Ne": 20.786,
     "Na": 28.23,
     "Mg": 24.869,
     "Al": 24.2,
@@ -1050,6 +1053,7 @@
     "P": 23.824,
     "S": 22.75,
     "Cl": 33.949,
+    "Ar": 20.786,
     "K": 29.60,
     "Ca": 25.929,
     "Sc": 25.52,
@@ -1067,6 +1071,7 @@
     "As": 24.64,
     "Se": 25.363,
     "Br": 75.69,
+    "Kr": 20.786,
     "Rb": 31.060,
     "Sr": 26.4,
     "Y": 26.53,
@@ -1082,18 +1087,36 @@
     "Sb": 25.23,
     "Te": 25.73,
     "I": 54.44,
+    "Xe": 20.786,
     "Cs": 32.21,
     "Ba": 28.07,
     "Hf": 25.73,
     "Ta": 25.63,
     "W": 24.27,
+    "Re": 25.48,
+    "Os": 24.7,
     "Ir": 25.10,
     "Pt": 25.86,
     "Au": 25.418,
     "Hg": 27.983,
     "Pb": 26.65,
     "Bi": 25.52,
+    "Rn": 20.786,
     "La": 27.11,
+    "Ce": 26.94,
+    "Pr": 27.20,
+    "Nd": 27.45,
+    "Sm": 29.54,
+    "Eu": 27.66,
+    "Gd": 37.03,
+    "Tb": 28.91,
+    "Dy": 27.7,
+    "Ho": 27.15,
+    "Er": 28.12,
+    "Yb": 26.74,
+    "Lu": 26.86,
+    "Ac": 27.2,
+    "U": 27.665,
 }
 
 # ionization energies (J/mol)