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Material migration and surface improvement using electrical discharge machining has become a key research area in the last two decades. Material may migrate to the machined surface of workpiece either from the tool electrode or from powder mixed in dielectric. This paper reports the results of experimental study carried out to evaluate the improvement in machined surface properties of OHNS die steel machined by electrical discharge machining using tungsten powder mixed in the dielectric medium. Gap current, pulse on time and pulse off time were taken as process parameters and micro-hardness of the machined surface was taken as the response parameter. Scanning electronic microscopy showed the topography of the machined surface, there are discrete craters along with some volcanic features, and many spherical droplets left on the EDmed surface, which indicate that the material removal mechanism is melting and evaporation. Spectroscopic and EDS analysis show substantial transfer of tungsten and carbon to the workpiece surface and an improvement of more than 100% in micro-hardness for all the trial conditions. Presence of tungsten was observed on all machined surfaces in the form of intermetallic compounds with iron, as carbides and in the form of alloyed cementite. Presence of carbon was observed on all machined surfaces in the form of solid solutions in ferrite and cementite phases or their independent hard carbides. These formations caused significant increase in microhardness. This was confirmed by the XRD analysis. Tribological analysis showed that coefficient of friction is higher for PMEDM work materials which …