Using an isolated neonatal rat spinal cord preparation, we have studied the ability of hydrogen peroxide to act as a source of oxygen for mammalian central nervous system (CNS) maintained in vitro. We report here that hydrogen peroxide, in low concentrations (0.001-0.004%), can effectively provide the only source, or act as a supplementary source of oxygen. This is brought about via the intracellular enzyme catalase which catalyzes the conversion of H2O2 into molecular oxygen and water.