Tungsten oxide (WO3) is a wide band gap semiconductor (~ 3.2 eV), which exhibits excellent properties suitable for the development of integrated chemical sensors and electrochromics. N-type conductivity coupled with selectivity and sensitivity to certain type of chemicals make WO3 thin films interesting for NOx and H2S sensors. The present work was performed to understand the effect of oxygen partial pressure on the microstructure, optical and electrical properties of WO3 thin films and optimize the conditions to produce materials suitable for sensor applications. WO3 thin films were produced by the reactive RF magnetron sputtering. The films were grown at various reactive gas pressures(2.3 – 5.6mTorr) by changing the oxygen flow rate while keeping the deposition temperature fixed at 400oC. Optical spectroscopy analysis of the grown films indicates that optical properties are sensitive to the oxygen partial pressure. The spectral transmission of the films increased with the increase in oxygen concentration. The band gap of these films was found to be increasing from 2.6 eV to 3.25 eV with increasing oxygen pressure. Electrical conductivity {~10-2 (Ω-cm)-1} measurements indicate that there is a correlation between the growth conditions, optical and electrical properties.