The catalytic property of H-beta zeolite in the methylation of o-toluidine was compared to that of other acidic zeolites, viz. HY, H-MOR, H-ZSM-5 and H-FER. The H-beta catalyst showed higher conversion of o-toluidine, the main product being 2,4-xylidine. The selectivity towards 2,4-dimethylaniline (2,4-xylidine) was about 69% (at 400degreesC over H-beta zeolite and was selective than the other zeolites under study. However, the other isomer (2,6-xylidine), over all zeolites, was formed in very less quantities (>4%). All the reaction parameters, viz. reaction temperature, weight hourly space velocity (WHSV), molar ratio of the reactants and time on stream was found to be profound effect on the conversion and selectivity of the product distribution. A detailed study of these reaction parameters was carried out over H-beta zeolite. (C) 2002 Elsevier Science B.V. All rights reserved.