Abstract: A process for preparing a polyarylene thioether, comprising oxidation coupling polymerizing with oxygen and a catalyst in the presence of an acid, at least one compound selected from the group consisting of thiophenols of the formula (II): ##STR1## wherein R.sup.9 to R.sup.12 are identical or different and each is hydrogen, alkyl having 1 to 10 carbon atoms, halogen or alkoxyl having 1 to 10 carbon atoms. Reaction conditions of the process are very mild, and the process is relatively simple and easy. In addition, the process is commercially advantageous in that very inexpensive reactants and catalysts can be used.