Hydrophobic modification of sulfonic acid (SO3H)-functionalized mesoporous silica (SO3H-MS) was successfully achieved by the grafting of triethoxyfluorosilane (TEFS) as a silylation reagent. After surface modification, SO3H-MS maintained mesoporous structure with large surface area and exhibited less water adsorption capacity. The grafting of a suitable amount of TEFS on SO3H-MS was effective for improvement of the catalytic performance as a solid acid catalyst in Friedel-Crafts alkylation. (C) 2014 Elsevier B.V. All rights reserved.