The solid state interactions in the ZnSO4.7H(2)O-MeO (Me = Cd, Pb, Ca, Mg) and CuSO4.5H(2)O-MeO (Me = Zn, Cd, Pb, Ca, Mg) systems, sulphate-ferrite systems, double sulphate systems and triple system FeSO4.7H(2)O-CuSO4.5H(2)O-ZnSO4.7H(2)O have been studied using DTA, TGA and X-ray diffraction analysis. The degrees of sulphatization of the studied oxides and ferrites and the phase composition depending on the temperature have been determined. The obtained results are discussed in terms of hydrometallurgical processing of zinc and copper-zinc concentrates.