The heat capacity of the natural zeolite gmelinite Na1.39K0.01Ca0.21Fe0.01Al1.83Si4.17 O-12 . 5.87H(2)O was investigated from (5.8 to 302.2) K. The measurements were carried out using a small calorimeter cell of internal volume of 2 cm(3) sealed with a threaded lid. To test the accuracy of the calorimetric system, the heat capacity of benzoic acid was measured from (5.6 to 312) K and compared with reliable reference data. Experimental data on the molar heat capacity Cp,m of gmelinite are listed, together with the tabulated thermodynamic functions. Anomalous behavior of the Cp.m function was found at T > 160 K. It is suggested that the additional contribution to the heat capacity is a result of the disordering in the (water, cations) subsystem of gmelinite.