Zirconyl oxalates of cobalt, cadmium, nickel and copper were prepared and characterized by chemical analysis and X-ray powder diffraction. Their pyrolysis was investigated using TG, DTG, DTA, mass spectroscopy and infrared techniques. The decomposition, in all cases, takes place in four steps : dehydration, and decomposition of the oxalate groups to give oxycarbonate, carbonate and oxides. The end products are simple oxides, except in the case of cadmium when cadmium zirconate CdZrO3 is obtained.