A highly convenient and efficient one step procedure for the synthesis of polystyrene thiol resin from Merrifield resin is described. Potassium O,O-diethyl thionophosphate is used as a thiolating reagent for the conversion of halogen (chloro) group to thiol functionality in refluxing DMF. By a simple procedure chloro methylated cross-linked polystyrene was thiolated through a nucleophilic substitution reaction. The modified beads were characterized by IR, laser Raman spectroscopy and elemental analysis. Evaluations of the functionalized beads were done by their halide scavenging and chelating efficiency. The novel feature of this method is simple and safe reaction, shorter reaction time and efficient loading of thiol functionality. (C) 2009 Elsevier Ltd. All rights reserved.