The products of toluene alkylation (p-ethyltoluene (p-ET) and m-ethyltoluene (m-ET)) are used for the production of methylstyrenes. The polymers formed from methylstyrene have advantages in comparison with polystyrene: lower density and higher glass transition temperature [Styrene-Its Polymers, Copolymers and Derivatives, Reinhold, New York. 1952] [1]. Moreover, the production of polymethyl styrenes enables one to use toluene as a substitute of benzene in petrochemical synthesis [From Hydrocarbons to Petrochemicals, Gulf, Houston, 1981] [2]. As a result of the syntheses of high-silica zeolites (HSZs) of the type ZSM-5, a new process of selective production of p-ET and m-ET mixture, suitable for polymerization, has been developed (New Monomers and Polymers, New York, 1983, Catal. Rev. 26 (1984) 597] [3,4]. In this paper. the optimal conditions of alkylation of toluene by ethanol using pentasil zeolites as catalysts are described.