The potential of potassium thioacetate as a new sulfur reagent in the nucleophilic displacement polymerization of aromatic haloaromatic compounds was investigated. Aromatic halogen compounds underwent nucleophilic substitution and formed the corresponding aryl sulfides in good yields. The reaction pathways were studied with the help of model compounds using C-13 NMR spectroscopy. A three-step process with the formation of S-aryl thioacetate and thiolate as intermediates is put forward. The effective use of the reagent in polythioarylene synthesis was explored. Polythioetherketones, polythioethersulfones and poly(thio-1,4-phenylene) were prepared in good yields. Potassium thioacetate seems to be a milder sulfur nucleophile as compared to the conventional alkali sulfides which usually yield higher molar mass compounds. (C) 2000 Elsevier Science Ltd. All rights reserved.