Exfluor Research Corporation has recently developed a technology for preparing mono- and di-basic perfluorocarboxylic acids in very high yields. The carboxylic acid functionality can be converted to various other functionalities such as alcohols, amines, halides, sulfonates, etc. which can then be used as fluorocarbon intermediates for the synthesis of high-performance fluorelastomers. This approach offers many advantages over the more classical routes to fluorocarbon elastomers. Namely, polymers made in this manner should be considerably less expensive. Efforts will be made to synthesize medium-molecular-weight (800-5000) perfluoropolyether dibasic carboxylic acids using newly developed direct fluorination technology. The research will focus on optimizing the fluorination conditions so that well defined products can be obtained in high yields. In order to accomplish this, side reactions leading to cross-linking, chain degradation, and loss of acid functionality must be avoided.