Zr-SBA-15 materials were synthesized and the activity of the catalysts was investigated in the alkylation of aromatics with benzyl chloride. While Zr-SBA-15 materials needed more than 12 h of reaction to achieve quantitative conversion, an unusually high catalytic activity was observed for reused materials that provided quantitative conversions of starting material in less than I h. This dramatic increase in activity observed for reused and/or treated Zr-SBA-15 in the alkylation of aromatics with benzyl chloride points to the formation of novel highly acidic Lewis ClxZr-O-Si species on the catalyst surface. (C) 2009 Elsevier B.V. All rights reserved.