Thermal decomposition processes taking place in solid state complex of Zn1-xMnxC2O4·2H2O have been investigated in air using TG-DTG/DTA, XRD and TEM techniques. TG-DTG/DTA curves showed that the decomposition proceeded through two well-defined steps with DTA peaks closely to correspond to the weight loss. XRD and formed under nonisothermal conditions, the activation energies were estimated by Friedman and Flynn-Wall-Ozawa(FWO) methods, and the most probable kinetic model has been estimated with multiple linear regression method.kJ/mol, respectively.