ZnO nanoparticles (NPs) were anchored to SiO2 spherical nanoparticles by hydrolysis and condensation of Zn(CH3COO)(2) in the presence of SiO2. The ZnO/SiO2 NPs were then blended with isoprene rubber. The immobilization of ZnO NPs on the silica surface, due to covalent Si-O-Zn bonds provides a homogeneous dispersion of zinc in the rubber matrix and increases the accessibility of the curative reactants to Zn2+ ions. This improves the efficiency of the rubber curing and reduces the amount of used ZnO. (C) 2015 Elsevier B.V. All rights reserved.