The authors have grown high quality WO3 nanowires and fabricated devices with single and multiple nanowires. Devices with single WO3 nanowire exhibit n-type semiconducting behavior and the conductivity increases with hydrogen annealing. The authors also demonstrate significant gas sensitivity of multi-WO3 nanowire devices at room temperature. The sensitivity measurements are carried out in a field-effect transistor geometry with many nanowires connected in between the source and drain electrodes. The sensitivity can be tuned with gate voltages, which will be useful for several applications where controlled gas adsorption is required.