The separation and determination of the cobalt in different oxidation states in cobalt neodecanoate were investigated. The effective separation of divalent cobalt， Co (II)， and trivalent cobalt， Co (III)， was carried out by using acetylacetonate since the formed complexes had different solubility. The determination of Co (II) content in cobalt neodecanoate was carried out by using complexometric titration and based on the difference in stability constant of the complexes. Through this method， separation and determination of the cobalt in self-made and commercial neodecanoate cobalt samples were successfully achieved.
