The investigation of the heat capacity of a natural specimen of copper phosphate pseudo-malachite Cus(PO4)(2)(OH)(4) in the temperature range between 4.2 K and 320 K has been carried out by the method of low-temperature adiabatic calorimetry. Tabulated values of the heat capacity and thermodynamic functions of the mineral including the changes of entropy and enthalpy and the Gibbs function of free energy have been calculated. The standard values of thermodynamic functions of pseudomalachite at T=298.15 K are C degrees(p.m) = (385.43 +/- 0.41)J mole(-1) K-1, Delta S-T(0)degrees(m) = (412.16 +/- 0.61)J mole(-1) K-1 Delta H-T(0)degrees(m)= (63681.5 +/- 57.0)J mole(-1), F degrees(m) = (198.57 +/- 0.47) J mole(-1) K-1. In the low-temperature area 0 < (T/K) < 22.69 an anomaly has been registered in the variation of the heat capacity of the mineral, for which the lattice constituent has been determined. The contribution of anomalous component into entropy and enthalpy of the mineral is Delta S-tr= (5.772 +/- 0.081) J mole(-1) K-1, Delta H-tr = (29.94 +/- 0.42) J mole(-1). (C) 2010 Elsevier B.V. All rights reserved.y