Tungsten cobalt carbides and oxides can be obtained via a single-step pyrolysis of an organometallic single-source precursor ( 5 -C 5 H 5 )(CO) 3 WCo(CO) 4 (1). Pyrolysis of 1 in an oxygen atmosphere produced WCoO 4 at 600°C. In a nitrogen atmosphere W 6 Co 6 C was obtained when 1 was heated at 700°C. However, under vacuum, the pyrolysis of 1 produced the other phase-W 3 Co 3 C-at 700°C. Both carbides were contaminated with graphitic carbon, as indicated by their ESCA spectra. Powders that were obtained by using these procedures had particle sizes of up to 100 µm. Micrography showed that the particles were porous, which indicated outgassing during pyrolysis.