The effect of an electric current on the tribological properties of WC cemented carbide were studied. Cemented carbide bars having a composition of 90% WC, 8% Co, 1.8% TaC, 0.2% NbC with dimensions of 5×6.5×20 mm were mounted in a sclerometer. A d.c. current with densities in the range of 0–90°A/cm 2 was injected parallel to the long axis of the bar during the test. The surfaces were examined by scanning electron microscopy, and by X-ray photoelectron spectroscopy. To measure wear and friction, an indenter with loads of 1.5 and 3.5 N was drawn over the surface of the test sample with a controlled velocity of 0.2 mm/s for 100 cycles. It was found that the scratching process fractured the carbide grains. The fractured carbides were agglomerated and compacted, forming a thick tribo film. Tungsten oxide WO 3 was found in the scratch track after scratching with current injection. With the injected current of 90 A/cm 2 the track width increased by a factor of 1.4 and 3 and the friction coefficient increased by a factor of 1.5 and 2 with a load of 1.5 and 3.5 N, respectively, as compared to scratching without a current.