Poly(styrene-ran-styrenesulfonic acid) and poly (styrene-block-styrene sulfonic acid) with low polydispersity were prepared using nitroxide-mediated living radical polymerization technique. Random or block copolymerization of styrene and neopentyl p-styrenesulfonate smoothly proceeded by AIBN/2,2.5,5-tetramethyl-4-diethylphosphono-3-azahexane-3-nitroxide initiating system. Transformation of the sulfonate ester to sulfonic acid was carried out by the reaction with trimethylsilyl iodide or by thermolysis at 150 degreesC. Those polymers showed amphiphilic characters.