The alkylation of toluene by ethanol has been investigated. Low-concentration aqueous solutions of ethanol were used, modelling the product of fermentation processing of renewable feedstock, and the catalyst was a high-silica zeolite of the pentasil type. It has been shown that excess water in the reaction mixture has a very favourable effect on process selectivity with respect to ethyltoluenes, which reaches 99-100% with the complete absence of the ortho-isomer and a para-isomer content of up to 92%.