Power MOSFETs have important applications in space systems; particularly in dc/dc power conversion. Transistors used in the space environment are subject to the effects of exposure to the natural radiation environment in space. Among the effects of ionizing radiation are shifts in threshold voltage and reduction of carrier mobility. In this work, the total-ionizing-dose-induced degradation of two switching power converters is examined. The MOSFETs for two switching converters were irradiated with a Co-60 source and their performance was evaluated in buck and boost converters. The experimental results agree well with values obtained from SPICE simulations. (C) 1998 Elsevier Science Ltd. All rights reserved.