The radiation-induced changes in the electrical and proton conductivities of hydrogen (H or D)-doped BaCe0.9Y0.1O3 (-) (delta) were investigated by performing irradiation using 1.8-MeV electron beams at ionization dose rates of 10-1000 Gy/s and an irradiation temperature of 473 K. For dose rates below 300 Gy/s, radiation-induced conductivity (RIC) occurred due not only to electronic excitation but also to the increased hydrogen diffusion caused by the ionizing effects of radiation. For dose rates above 300 Gy/s, the base conductivity and RIC were gradually reduced as the irradiation dose increased up to a dose of approximately 8.0 MGy; this is indicative of radiation-induced electrical degradation (RIED). The dependence of RIC and RIED on the dose is not affected by the presence of doped hydrogen. Radiation-enhanced diffusion of the constituent oxygen in BaCe0.9Y0.1O3 (-) (delta), not only leads to the occurrence of RIC and RIED but also suppresses the migration of protons activated by the ionizing effects of radiation. This suppression occurs because of the formation of Ba and Ce hydroxides and/or hydrides on the surface of the irradiated samples; the formation of these compounds is revealed by XPS and optical absorption spectra. (C) 2009 Elsevier B.V. All rights reserved.