Liquid phase alkylation of benzene to linear alkyl benzene (LAB) with alpha-olefins has been investigated with 12-silicotungstic acid supported on zirconia (STA/ZrO2) as the catalyst. Among the catalysts, 15 wt.% STA/ZrO2 calcined at 750 degrees C was found to be most active than others in the alkylation reaction. The total amount of acid sites of different STA loaded catalysts were estimated by TPD of NH3 and 15 wt.% STA/ZrO2 calcined at 750 degrees C was found to have the highest acidity and more active in the reaction. The optimization of reaction conditions of alkylation of benzene with 1-dodecene was performed with 15 wt.% STA/ZrO2 calcined at 750 degrees C by varying catalyst concentration (1-5 wt.% of reaction mixture); temperature, 373-423 K and benzene: 1-dodecene (1-dd) molar ratio, 5-15 in a Parr autoclave under N-2 pressure. Under the optimized reaction conditions, conversion of 1-dodecene (50.8%) gave high selectivity to 2-phenyl dodecane (47.1%) and the remaining 3-, 4-, 5- and 6-phenyldodecanes in 4 h. The reaction was found to be heterogeneously catalyzed and no contribution from homogeneous (leached) STA into the reaction medium. (c) 2005 Elsevier B.V. All rights reserved.