In order to use a polymer-metal complex as a catalyst of UV cure type electrodeposition paint, water soluble polymer-Co (III) complexes having a polymeric ligand (PVP : poly-4-vinylpyridine) such as cis- [Co (en) 2 PVP·Cl] Cl2 and cis-α- [Co (trien) PVP·Cl] Cl2 were synthesized. The influence of neutralization and coulombs passed on the stability of aqueous solution of these complexes was studied by measuring the shift of the first absorption band λ1 (-500nm) or the change of pH. In addition, the electrodeposition was carried out, using an acrylic paint system contained 0.1% Co (III) -PVP complex. (1) λ1 was influenced by the type of neutralizing base and shifted about 3-12nm to high wave numbers in the order of TEA, NH4OH and NaOH. (2) When a direct electric current was passed through the aqueous solution of these Co (III) -PVP complex, the pH of these solution considerably increased with coulombs passed and finally became about 9. Consequently, it seems that an increase of the pH results from liberation of ethylendiamine or triethylentetramine by the decomposition of the Co (III) -PVP complex. (3) A migration efficiency of each Co (III) -PVP complex for the deposited films was between 8.2 to 13.2%. When the films were irradiated by UV radiation, crosslinking was remarkably accelerated and a catalytic action of the Co atom was recognized. It can therefore be presumed that the Co atom in the deposited films exists in the form of Co (II) or Co (III) complex.