Vapor-phase methylation of toluene with methanol and isopropylation of toluene with 2-propanol has been investigated in a down flow reactor under atmospheric conditions using N-2 gas carrier over a series of surface modified and unmodified ZSM-5 (Si/Al = 60-170) loaded with H3PO4, differing in the external surface treatment of the zeolites. The feed molar ratios of toluene/methanol and toluene/2-propanol were varied over a wide range (8-0.125), and the optimum feed ratio of toluene/alcohol was less than 0.5 in both cases. Space velocity employed in toluene methylation reported as WHSV (toluene) = 1.2 h(-1), and the space velocity employed in toluene isopropylation reported as WHSV (toluene) = 0.8 h(-1). The methylation reactions were carried out in the temperature range of 623-773 K, and the isopropylation reactions were carried out in the temperature range of 483-583 K. Atmospheric pressures was maintained in all runs. Catalysts containing 0-4.9 wt.% P were prepared using modified and unmodified ZSM-5 zeolites, and their catalytic performance for vapor-phase alkylation of toluene with methanol and 2-propanol were investigated. The optimum phosphorous content for methylation was 2.1 wt.% P which was greater than the optimum phosphorous loading for isopropylation (0.7 wt.% P). (c) 2006 Elsevier B.V. All rights reserved.