W-Si-N coatings were deposited by sputtering and their chemical composition, structure, thermal and oxidation behaviour were characterised. Si-containing films are essentially amorphous. W69Si31 film crystallises at 750 degrees C as alpha-W and W5Si3 phases whereas no significant structural transformations were observed for W24Si21N55 him up to 1000 degrees C. Ln both cases elemental diffusion (Si and N) for the substrate was detected after thermal annealing. These coatings present much better oxidation resistance than W and W45N55 coatings.