The polymerization of ethylene bis(alpha-ethylacrylate) to polyester was catalyzed with benzyl(bisdimethylglyoximato)(pyridine)cobalt(III). though the alpha-ethylacrylic ester does not radically homopolymerize, radical addition to the carbon-carbon double bond yields the corresponding radical. This radical readily reacts with the cobalt(II) complex involved to form a carbon-cobalt bond. Dissociation of the generated bond accompanying fast beta-hydrogen elimination results in a new carbon-carbon double bond and the cobalt hydride which rapidly adds to the ethylacrylate moiety to form a carbon radical which may react with the cobalt(II) complex. Through the sequence of these reactions, the novel polyester linkage was expected to be formed. Actually, the cobaloxime catalyzed reaction competed with radical propagation, and the polymer consisted of the polyester linkage (32%) and the consecutive ethylacrylate units with two types of unsaturated pendant groups (68%).