Two complexes trans-difluoro bis-(ethylenediamine) chromium (III) chloride 1.5 hydrate and mu-[(ethylenediamine) chromium (III) dichloro (ethylenediamine)] chloride were isolated and were characterized by elemental analysis and IR spectroscopy. The thermal behaviour of the two complexes on heating up to 800 degrees C in nitrogen atmosphere was examined by thermogravimetry (TG), DTG and differential thermal analysis (DTA). Thermal analysis showed three stages of decomposition of trans-[Cr(en)(2)F-2]Cl . 1.5H(2)O in the following order: (i) dehydration, (ii) deamination or loss of amine and (iii) total disruption of the complex to form Cr2O3 AS for [(Cr-2(en)(3)Cl-4)]Cl-2, its decomposition involved: (i) loss of the bridged ethylenediamine, (ii) loss of the two other ethylene diamines and (iii) disruption of the complex to form the oxide. Activation parameters were evaluated using the theory of absolute reaction rate and values of activation energy were found to be 38.3 and 103 kT mol(-1) for the dehydration and deamination of trans-[Cr(en)(2)F-2]Cl . 1.5H(2)O respectively, and 88.7 and 203 kT mol(-1) for the loss of bridged ethylene diamine and the other two ethylenediamines of [Cr-2(en)(3)Cl-4]Cl-2 molecules, respectively.