In this paper kinetics of thermal decomposition of oxalato coordination is stuided by gas chromatography. A kinetic equation of thermal decomposition is proposed. A computer program which was written in FORTRAN-IV language has been worked out to evaluate the activation energy and the Arrhenius pre-exponential factor. The results of calculation show that the equation is better agreement with the experimantal data. The activation step in decomposition of Fe(C2H4)3 is discussed on basis of calculation by EHMO method.