Tricadmium phosphite Cd-3(PO4)(2) (TriCd) and cadmium chlorapatite Cd-10(PO4)(6)Cl-2 (CdClap) were prepared by dry chemistry method. They were characterized by X-ray diffraction, IR spectroscopy and chemical analysis. Using an isoperibol calorimeter, the heat of solution of these products in 9% weight nitric acid solution were determined. They are (-147.3 +/- 2,1) kJ mol(-1) and (-261,6 +/- 1,1) kJ mol(-1) for TriCd and CdClap, respectively. Combining these results with the enthalpies of formation of [Cd(NO3)(2), 4H(2)O], H(3)PO(4)aq, HClaq and H2O and their enthalpies of solution in the same solvent, leads to the standard enthalpies of formation of these Cd-phosphates. These quantities are: -2626 kJ mol(-1) for TriCd and -8463 kJ mol(-1) for CdClap.