This invention is a process for preparing Group I-B and II-B metal, preferably copper, salts of polyolefinic substituted dicarboxylic acids. The method involves the step of introducing substantially less than a stoichiometric amount of a short chain carboxylic acid (such as acetic or propionic acid), in a stagewise fashion, to a mixture of a source of the corresponding Group I-B or II-B metal (such as an oxide or hydroxide) with the polyolefinic substituted dicarboxylic acid. The product salt is then recovered.