The effects of oxygen pressure on meba2cu3ox (me = y, sm, or gd) and on bi-based sueperconductors were investigated for enhancing the superconductivity of new ceramic compounds. Each sample was treated in pure oxygen at various temperatures and pressures, carefully weighed before and after oxygenation, and its superconductivity determined by susceptibility measurements. Pressures up to about 180 atm enhance the critical onset temperatures for superconductivity by about 4 k, and 3,000 atm, by about 7 k. At 3,000 atm, the smba2cu3ox sample partially dissociated, while the gd sample remained stable. Bi-based superconductors are completely dissociated under oxygen pressures as low as 125 atm at 700 deg c. This research is a joint effort by the U.S. Bureau of Mines, the National Institute of Standards and Technology, E.I. Dupont de Nemours and Company, and Sandia National Laboratories.