A WC-Co coaling was sprayed by the high-velocity oxy fuel process using a feedstock of tungs(en carbide clad wilh cobalt. The struccture of the sprayed coating was characterized by x-ray diffractiun (XRD), dif-ferential scanning caloriulptry (DSC), and differential thermal analysis (DTAL It was found that an amorphous phase of Co-W-C lernary alloy observed as a large, broad peak in the XRD paltern can he formed in tile as-sprayed WC-Co coating. The DSC, DTA. and XRD analyses revealed that Ihe amor-phous phase cryslallized al a lemperature of around 873K to metallic cobalt. Co6W6C, and tuugslen witb appreciable precipilation of free carbon. The heat treatment of as-sprayed WC-Co coating at a high tem-perature of 1173K suggests that annealing at a temperature higher than about i104 K will promote Ihe reaction of lungsten and cobalt with carbon to form the complex carbide Co6W6C.