Electrodes of the type base metal (Ti, Zr, and Ta)-catalytic coating (RuO2, IrO2, PtO2, TiO2, ZrO2, and Ta2O5) for O evolution in acidic solns. were prepd. and characterized. The electrodes were tested in 30% H2SO4 solns. at 80 Deg. The susceptibility to thermal oxidn. was in the order Nb > Ta > Zr > Ti and to anodic oxidn. was the order Nb > Zr > Ti > Ta. [on SciFinder (R)]