The heat capacity measurements of the crystalline phosphate CsMgPO4 of a tridymite structure were performed between T = (7 and 650) K. The thermodynamic functions C-p,C-m degrees/R, Delta H-T(0)m degrees/RT, Delta S-T(0)m degrees/R, and Phi(m)degrees/R were calculated and the fractal dimension D-fr evaluated. From the solution reaction calorimetry, the standard enthalpy of CSMgPO4 formation at T = 298.15 K was found. Thermochemical parameters of formation Delta(f)G(m)degrees and lgK(f,m)degrees were determined by combining the data obtained by these techniques. (C) 2007 Elsevier Ltd. All rights reserved.