diff --git a/ProcessLib/HydroMechanics/CreateHydroMechanicsProcess.cpp b/ProcessLib/HydroMechanics/CreateHydroMechanicsProcess.cpp
index 2a5b33ecb18e1e941935d96f5a9125424e1cec54..240f0593744fb7b902e15d76432dacf219e7ac3d 100644
--- a/ProcessLib/HydroMechanics/CreateHydroMechanicsProcess.cpp
+++ b/ProcessLib/HydroMechanics/CreateHydroMechanicsProcess.cpp
@@ -162,12 +162,6 @@ std::unique_ptr<Process> createHydroMechanicsProcess(
             "reference_temperature", std::numeric_limits<double>::quiet_NaN());
     DBUG("Use 'reference_temperature' as reference temperature.");
 
-    //Specific gas constant
-    double const specific_gas_constant =
-        //! \ogs_file_param{prj__processes__process__HYDRO_MECHANICS__specific_gas_constant}
-        config.getConfigParameter<double>(
-            "specific_gas_constant", std::numeric_limits<double>::quiet_NaN());
-    DBUG("Use 'specific_gas_constant' as specific gas constant.");
 
     auto const fluid_type =
         FluidType::strToFluidType(
@@ -186,8 +180,7 @@ std::unique_ptr<Process> createHydroMechanicsProcess(
         materialIDs(mesh),     std::move(media_map),
         std::move(solid_constitutive_relations),
         initial_stress,        specific_body_force,
-        reference_temperature, specific_gas_constant,
-        fluid_type};
+        reference_temperature, fluid_type};
 
     SecondaryVariableCollection secondary_variables;
 
diff --git a/ProcessLib/HydroMechanics/HydroMechanicsProcessData.h b/ProcessLib/HydroMechanics/HydroMechanicsProcessData.h
index af8a6fab75d2f71d9c7d4de07c3ba4309f761e60..3eb53cb5d7f9f5b63164cffd1d2a746045c3fd5c 100644
--- a/ProcessLib/HydroMechanics/HydroMechanicsProcessData.h
+++ b/ProcessLib/HydroMechanics/HydroMechanicsProcessData.h
@@ -61,10 +61,6 @@ struct HydroMechanicsProcessData
     double const reference_temperature =
         std::numeric_limits<double>::quiet_NaN();
 
-    /// Specific gas constant. A scalar quantity.
-    /// Only used for ideal_gas fluid_type
-    double const specific_gas_constant =
-        std::numeric_limits<double>::quiet_NaN();
 
     /// Fluid type. Enumerator with possible values:
     /// incompressible_fluid, compressible_fluid, ideal_gas