Peroxide vulcanization leads to formation of carbon-carbon cross-links, resulting in some cases in poor mechanical properties of the vulcanizates, which restricts the application of such materials in industrial goods. Therefore to improve the properties of the obtained vulcanizates coagents are added to the rubber compounds. Coagents are incorporated in the polymer network by covulcanization of coagent domains with elastomer matrix. As a result, coagents affect the cross-link structures and the network topology of the vulcanizate, resulting in improvement in strength properties and increased cross-linking efficiency. In these studies we applied nanostructured zinc oxide as a coagent in peroxide vulcanization of hydrogenated butadiene-acrylonitrile elastomer HNBR (Therban A3704). The surface of nanoparticle zinc oxide was modified with unsaturated acids and esters such as itaconic acid, acrylic acid and monoallyl maleate. The influence of modified nanoparticle zinc oxide on cross-link density and mechanical properties of vulcanizates was estimated. (C) Koninklijke Brill NV, Leiden, 2009