The kinetics and mechanism of thermal decay of an unsaturated copper carboxylate, Cu(OCOCH=CH2)(2) (CuAcr(2)), have been studied. At 190-240 degrees C the rate of thermal decay can be adequately described by a set of zero and first order rate equations. The initial rate of decay, W-0, is equal to 1.7.10(17)exp[-48500/(RT)] s(-1). The decay products of CuACr(2) were analyzed by IR and mass spectroscopy as well as by optical microscopy. It has been established that the thermal decay of the monomer under study is accompanied by polymerization, fragmentation, and recombination processes in the solid phase which produce polymeric agglomerates.