Abstract WSiN films were deposited by reactive sputtering in a N 2+Ar atmosphere from a W target incrusted with different number of Si pieces. The coatings present different crystallographic structures from the crystalline α-W and W 2N to amorphous phase. Crystalline films have very low grain sizes from 15 down to 3 nm. For WSi films there is a good correlation between the increase of the hardness and both the increase of lattice parameter and decrease of grain size. However, for N containing films these tendencies are not systematically observed. The homogeneity in the lattice distortion seems to be more adequate to interpret the hardness variation. Generally, crystalline films have higher hardness (35–41 GPa) than amorphous coatings (21–31 GPa).