The azo initiator, sodium-{4-(4-hydroxy-phenylazo)-benzenesulfonate (SHPBS)}, has been synthesized by coupling reaction with sodium-(p-sulfonate benzene diazonium chloride) and phenol. Unsymmetrical azo group leading to weak azo bond in case of SHPBS resulted in dissociation at lower temperature (25 degrees C) to produce free radicals. Its versatile solubility (soluble in aqueous and organic solvents), generation of free radicals at 25 degrees C, and its application without mechanical stirring are the added greater advantage over commercially available azo initiators (AIBN, etc.). The SHPBS has been characterized by FTIR, 1H-NMR spectroscopies, and thermal analysis. It has been observed that various monomers such as AM, AA, IPAM, and AMPS which have been polymerized with SHPBS have led to high molecular weight polymers at shorter reaction time. (c) 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013