The oxidation of ethylene glycol (HOCH2CH2OH) and 1,2-propanediol (HOCH(CH3)CH2OH) was investigated over Pd/C, Au/C, and a series of bimetallic catalysts prepared by electroless deposition of Au onto Pd/C. In order to explain the enhanced activity of the bimetallic catalysts, the oxidation kinetics of selectively deuterated reagents were investigated. On Au/C and 0.61Au-Pd/C, a primary kinetic isotope effect was observed for d(4)-ethylene glycol (HOCD2CD2OH), indicating that C-H bond scission is the rate-limiting step. Density functional theory and X-ray photoelectron spectroscopy experiments show a correlation between an increased electron density in Au core orbitals and more favorable thermodynamics for C-H scission as Au is added to Pd. Computational studies suggest that the rate enhancement on the bimetallic surfaces compared to Pd is likely due to a decrease in coverage of strongly bound adsorbates, while the enhancement over Au is likely due to a decrease in the barrier for C-H scission. (C) 2013 Elsevier Inc. All rights reserved.