Abstract. This work was aimed at achieving an optimal deposition process by pulsed laser ablation (PLA) on large area substrates, using pure tungsten as target. The films were deposited at different: wavelengths (355/532/1064 nm), fluences (1.5, 5 and 10 J/cm 2 ), oxygen pressures (100 and 200 mTorr), substrate temperatures (room temperature, 200, 300, and 400°C). The morpho-structural and compositional investigations have been carried out by profilometer, scanning electron microscopy, X-ray diffraction, Rutherford backscattering spectroscopy and Fourier transform infrared spectroscopy. The study has shown that optimal conditions for tungsten deposition on large area surfaces are at 355 nm/ 5 J/cm 2 . Amorphous, orthorhombic and triclinic phases WO 3 films were obtained.