Ternary W-Si-N thin films have been reactively sputter-deposited from aW5Si3 target at different nitrogen partial pressures. The composition hasbeen determined by 2.2 MeV4He+ beam, the structure byx-ray diffraction and transmission electron microscope, the chemical bondsby Fourier transform - infrared spectroscopy and the surface morphology byscanning electron microscopy. Electrical resistivity was measured by fourpoint probe technique on the as grown films. The film as-deposited isamorphous with the Si/W ratio increasing from about 0.1 up to 0.55 with thenitrogen content going from 0 to 60 at%. The heat treatments up to 980 °Cinduce a loss of nitrogen in the nitrogen rich samples. Segregation ofmetallic tungsten occurs in the sample with low nitrogen content (W58Si21N21). Samples with high nitrogencontent preserve the amorphous structure, despite of the precipitation of amore ordered phase inferred by FT-IR absorbance spectrum of the layertreated at highest temperature. The surface morphology depends upon thenitrogen content; the loss of nitrogen induces the formation of blisteringand in the most nitrogen rich sample the formation of holes. Electricalresistivity preliminary results on the as grown layers range between 500 and4750 μωcm passing from the lowest to the highest N concentration.