Silica-supported H3PW12O40 (H3PW) catalysts (8, 15, 20 and 25 wt.% H3PW) were prepared and their catalytic activities were evaluated in benzene transalkylation with C9+ aromatics, using an industrial stream. This reaction is a convenient way to upgrade the low value of the stream produced in naphtha reforming and gasoline pyrolysis, by improving the production of xylenes. It was found that the activity and selectivity to xylenes changed with the acid loading and this was related to optimum acid strength and dispersion as well as specific surface area of the solids. The most active catalyst was the sample with 15 wt.% H3PW, which showed the adequate combination of the three parameters cited above. This solid was also the most stable, showing the lowest rate of deactivation under the reaction conditions, producing the least amount of coke. In addition, it presented the highest activity and selectivity to xylenes, even when compared to a mordenite commercial catalyst. Consequently, this catalyst represents a promising catalyst for industrial applications. (c) 2007 Elsevier BX All rights reserved.