The article details the development of a poly(para amino benzene sulfonic acid) modified glassy carbon electrode as a sensor for simultaneous determination of purine bases; guanine, adenine and uric acid. When 0.1 M NaOH was used as the supporting electrolyte the electro-oxidation of these analytes took place at well resolved electrode potentials which facilitated their simultaneous determination without any electrode fowling. The sensor response has been calibrated for both simultaneous and individual determination. Wide linear working concentration ranges and good detection limits were obtained for both. The selectivity of the sensor for simultaneous determination has been checked among these purine bases as well as in the presence of other possibly co-existing species. The sensor has been demonstrated to be efficient for determination of uric acid, guanine and adenine in acid denatured herring sperm DNA. The mechanistic and kinetic parameters such as charge transfer coefficient, number of electrons involved in the rate determining step, diffusion coefficient and heterogeneous rate constant for the electro-oxidation of these bases on the poly(para amino benzene sulfonic acid) modified glassy carbon electrode has also been determined. (c) 2018 The Electrochemical Society.