Thermogravimetry, derivative thermogravimetry (TG-DTG), and differential thermal analysis (DTA) have been used in the study of decomposition of hydrated ferrous (II) sulphate under air atmosphere. The kinetics of particular stages of FeSO4 . 7H(2)O decomposition were evaluated from the dynamic weight losses data. The values of the activation energy E, the preexponential factor A, and thermodynamic parameters of the each stages of the thermal decomposition were calculated from alpha(t) data by using the integral method by the applying the Coats-Redferns approximation.