Strontium(II) bis (oxalato) strontium(II) trihydrate, Sr[Sr(C2O4)2]·3H2O and mercury(II) bis (oxalato) mercurate(II) hexahydrate, Hg[Hg(C2O4)2]·6H2O have been synthesized and characterized by elemental analysis, reflectance and IR spectral studies. Thermal decomposition
studies (TG, DTG and DTA) in air showed SrCO3 was formed at ca. 500°C through the formation of transient intermediate of a mixture of SrCO3 and SrC2O4 around 455°C. Sharp phase transition from γ-SrCO3 to β-SrCO3 indicated by a distinct endothermic peak at 900°C in DTA. Mercury(II) bis (oxalato) mercurate(II) hexahydrate showed an inclined
slope followed by surprisingly steep slope in TG at 178°C and finally 98.66% of weight loss at 300°C. The activation energies
(E*) of the dehydration and decomposition steps have been calculated by Freeman and Carroll and Flynn and Wall's method and compared
with the values found by DSC in nitrogen. A tentative reaction mechanism for the thermal decomposition of Sr[Sr(C2O4)2]·3H2O has been proposed.