Novel copolymers of fluorinated olefins and maleic anhydride, maleic acid, dichloromaleic anhydride or dichloromaleic acid may be made by using as solvents for the maleic anhydride or acid a perfluorinated alkyl carboxylic acid, or liquid or supercritical hexafluoropropylene or carbon dioxide. The resulting polymers are useful as adhesives or compatibilizing agents for fluoropolymers, and in coatings.