Precursors of Co3O4 and Ag/Co3O4 composites with sheet-like shape were synthesized with assistance of ethylene glycol via a solvothermal process. The final samples were obtained by calcining each precursor at 400 degrees C. The as-prepared samples were identified and characterized by thermogravimetric analysis (TG) and differential thermal gravimetric (DTG) analysis, X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), and field emission scanning electron microscopy (FE-SEM). The Co3O4 and Ag/Co3O4 composite nanosheets were used as electrocatalysts modified on a glassy carbon electrode for p-nitrophenol and H2O2 reduction respectively in a basic solution. The electrocatalytic results showed that p-nitrophenol could be reduced by pure Co3O4 at a large peak current but a rather higher peak potential, and could be reduced effectively by Ag/Co3O4 composites at lower potential. Ag/Co3O4 composites with 6% Ag displayed the highest electrocatalytic activity for H2O2 reduction at the largest peak current and a lower peak potential. The reduction peak potentials of H2O2 all reduced a great deal using Ag/Co3O4 composite. (C) 2013 Elsevier B.V. All rights reserved.