Gold nanoparticles (similar to 3 nm, 4 wt% Au) dispersed on reduced graphene oxide (Au/rGO) surface were prepared via the reduction of gold (III) chloride using sodium citrate on reduced graphene oxide support. The chemical, morphological, and size analyses of Au/rGO by XRD, XPS, TEM, HR-TEM/EDS, AAS, and Raman spectroscopy revealed that the hybrid material comprised of a well-defined rGO support decorated with gold nanoparticles. The ensuing catalyst was evaluated for the oxidation of ethyl benzenes (yields up to 95%) and oxidative esterification of aldehydes (73-97%) using oxygen as an environmentally friendly oxidant in good to excellent yields; reusable and recyclable catalyst displayed high activity without the use of toxic organic solvents. (C) 2016 Elsevier B.V. All rights reserved.