Voltammograms of the low index planes of Pd and Pd(S)-[n(100) x (111)] electrodes have been studied in 0.1 M NaOH. The voltammograms are more complicated than those in acid solutions. An anodic peak due to the desorption of absorbed hydrogen is found on Pd(111) and Pd(100). No peak due to the hydrogen desorption is observed on Pd(110). The onset potentials of the oxide film formation are more negative than those in acid solutions. Coverages of the oxide film on Pd(111) and Pd(100) in 0.1 M NaOH are lower than those in 0.1 M HClO(4). The coverage on Pd(110), however, has the same value as the one in 0.1 M HClO(4). On Pd(S)-[n(100) x (111)] electrodes, oxide film formation at the step can be distinguished from the one at the terrace in 0.1 M NaOH. This result differs from that in H(2)SO(4) in which the oxide film formation gives no peak at the step. (C) 2008 Elsevier B.V. All rights reserved.