Heavy alkyl benzene (HAB) is produced as a side-product in linear alkyl benzene (LAB) manufacturing processes. Heavy alkyl benzene is a mixture of alkylated benzene rings with paraffinic side chains within the carbon range C11-C22. The proportion of components depends on the manufacturing process of LAB. In this work the most favorable sulfonation conditions of HAB produced in Isfahan linear alkyl benzene conditions are adjusted to maximize the reaction yield.