This study presents the synthesis of heavy alkyl benzene sulfonate (HABS) via liquid-liquid reaction of heavy alkylbenzene (HAB) with dilute liquid sulfur trioxide (SO3) in a rotating packed bed (RPB) combined with a stirred tank reactor (STR). The effects of different operating conditions including high gravity level (G), total liquid flow rate (Q(L)), SO3 concentration (zeta), SO3 dosage (phi), reaction temperature (T) and reaction time (theta) on HABS content (eta) were investigated, and the results revealed that high HAGS content of about 88% was achieved under the optimal operating conditions including G of 59, Q(L) of 62.8 Lh(-1) , zeta of 30%, phi of 1.1, T of 45 degrees C and theta of 4 min. The results indicated that the sulfonation reaction was basically achieved in the RPB of the combined reactor, and the time of the synthesis process was shortened. (C) 2016 Elsevier B.V. All rights reserved.