Using the adiabatic calorimetry method, the heat capacity of a non-stoichiometric niobium carbide, NbCy, in ordered (0.81 ≦ y ≦ 0.88) and quenched disordered (0.75 ≦ y ≦ 0.97) states is measured over the temperature range 80 to 300 K. It is found that in the temperature interval investigated an ordered niobium carbide has a higher heat capacity than a disordered carbide of the same composition. The effect of ordering on the heat capacity of niobium carbide is interpreted in terms of the order parameter functional method.