Thermogravimetry was used in the study of the kinetics of dehydration of MnSO4.5H(2)O, CuSO4.5H(2)O and 3CdSO(4).8H(2)O under static air atmosphere. The values of the kinetic and thermodynamic parameters for each stage of thermal dehydration were calculated from alpha(T) data by using the integral method, applying the Coats-Redfern approximation. The best model for all stages of dehydration is random nucleation model F I. The dependencies of enthalpy on entropy of activated complexes for different kinetic models were described. The linear relation was calculated between the Gibbs energy of activated complexes and the maximum dehydration rate temperature for analysed dehydration processes. (C) 2003 Elsevier Science B.V. All rights reserved.