Abstract : The initial experimental work on the high-field superconducting characteristics has started with an investigation of the effect of grain size on the critical field (H sub c)-critical current (I sub c) relationship. Measurements have been made which show an anomalous behavior of H sub c versus I sub c for a certain range of grain sizes. Future work will be directed toward obtaining a complete experimental and theoretical description of the relationship between the structural variations and the electrical characteristics. Initial experiments on the proper ties of superconducting thin filaments have been performed on samples consisting of lead imbedded in a copper matrix. The results have indicated that size-dependent behavior occurs before it would be expected on a theoretical basis. It is possible that the normal copper electrons are severely affecting the superconducting properties of the lead. Additional experiments are being planned to define the phenomenon more completely.