Structural effects on the oxygen reduction reaction (ORR) have been studied on the high index planes of Pt (n(1 1 1)-(1 II), n(1 1 1)-(1 00), n(1 0 0)-(1 1 1) and n(1 0 0)-(1 1 0)) using rotating disk electrode (RDE) in 0.1 M HClO4. The activity for the ORR increases with the increase of the step atom density on the surfaces with (1 1 1) terrace from n= infinity to n=5 (n is the number of terrace atomic rows), whereas the surfaces with (1 0 0) terrace do not show structural effects on the ORR activity. The activity of the surfaces with (1 1 1) terrace is higher than that on the surfaces with (1 0 0) terrace. The active sites for the ORR are located between the (1 1 1) terrace edge and the (1 1 1) terrace atomic row neighboring to the edge on Pt electrodes. (C) 2013 Elsevier Ltd. All rights reserved.