Ag-Pd nanoparticles with compositional ratios of 1:1 (Ag(1)Pd(1)), 2:1 (Ag(2)Pd(1)), and 4:1 (Ag(4)Pd(1)) and supported on multiwall carbon nanotubes (CNTs) were prepared by the self-regulated reduction of sodium dodecyl sulfate, and then, they were used as catalysts for oxygen reduction reactions (ORRs) in 1 M NaOH solution. Polarization curves showed that, among the prepared nanocatalysts, Ag(4)Pd(1)/CNT nanocatalysts showed higher activity. During the ORRs, two types of oxygen coverages given by the Temkin isotherm and Langmuir isotherm were observed for low and high overpotentials, respectively. Koutecky-Levich plots showed that the number of electrons involved in the ORRs catalyzed by Ag(1)Pd(1)/CNT, Ag(2)Pd(1)/CNT, and Ag(4)Pd(1)/CNT were 2.11, 1.88, and 2.25, respectively. These ORRs proceeded through a two-electron pathway. Polarization curve in the electrolyte with methanol revealed that Ag(4)Pd(1)/CNT has high methanol tolerance during ORRs. (C) 2010 Professor T. Nejat Veziroglu. Published by Elsevier Ltd. All rights reserved.