The glycerol electro-oxidation reaction (GEOR) can economically convert glycerol, a byproduct of biodiesel production, to glycolic acid. Herein, nanostructured Au catalysts were fabricated on a Si substrate by the electrochemical reduction of anodic-treated (RA-treatment) Au films, which tuned the surface area from 1 to 16 cm(2). Treatment of 0.1 M glycerol at 1.0 V (vs RHE) for 2 h in 1 M KOH solution afforded a glycerol conversion and glycolic acid selectivity of 50.9 and 47%, respectively. The RA-Au catalyst selectively afforded glycolic acid from glycerol due to the enhanced facet-dependent OH adsorption, especially at the (100) and (110) sites, as well as the increased surface area. RA treatment of a Au-coated Ni foam further enhanced the GEOR performance, affording 68.7% glycerol conversion and 41.2% glycolic acid selectivity at 1.0 V (vs RHE) within 2 h by providing more active sites.