The present work was undertaken in order to study the possibility of case hardening of a plain steel using the Plasma Transferred Arc (PTA) alloying process. It was found that, depending on the PTA operation parameters and cooling rates, either carburizing or case hardening can be obtained. The depth of carburizing reaches a depth up to 1 mm and can be pre-selected by adjusting the PTA operation parameters. Due to the beneficial effect of carburizing with the PTA alloying technique, wear resistance of the treated surface is significantly improved. (C) 2003 Kluwer Academic Publishers.