By combining cyclic voltammetry and potentiostatic current transients with measurements of the potential dependence of gold's reflectance at 520 nm, we provide unambiguous evidence that glycerol and gold oxidation compete for adsorbed OH, whereby the formation of gold oxide is retarded in the presence of glycerol and the formation of gold oxide inactivates the oxidation of glycerol. Potentiostatic current transients coupled with ATR-SEIRAS at potentials close to the onset of glycerol oxidation also suggest that the adsorption of carboxylates generated upon oxidation of glycerol leads to a progressive decrease of the electrocatalytic activity. However, both ATR-SEIRAS and experiments using a rotating-disk electrode suggest that the adsorption of these carboxylates is an equilibrium process. Therefore, using high flow rates should allow to keep the inhibition of the reaction at an acceptable level. These results are relevant for the design of fuel cells capable of generating electricity plus value-added chemicals from glycerol. (C) 2020 Elsevier Inc. All rights reserved.