diff --git a/thermosteam/reaction/_reaction.py b/thermosteam/reaction/_reaction.py
index 6e29507c..fdd83594 100644
--- a/thermosteam/reaction/_reaction.py
+++ b/thermosteam/reaction/_reaction.py
@@ -1125,7 +1125,6 @@ def copy(self, basis=None):
         copy._stoichiometry = self._stoichiometry.copy()
         copy._reactant_index = self._reactant_index
         copy._chemicals = self._chemicals
-        copy.chemicals = self.chemicals
         copy._X = self.X
         if basis: set_reaction_basis(copy, basis)
         return copy