In this work, we report on the gas sensing properties of n-WO3/p-porous silicon (PS) structures. Nanostructured WO3 films are deposited by simple chemical method via dip-coating of PS in tungsten hexachloride solution. The morphological and structural properties of the elaborated structures were investigated using Atomic Force Microscope (AFM), Raman and Fourier Transform Infrared (FTIR) Spectrometers. The NO2-sensing performances of the sensor were measured at different operating temperatures ranging from room temperature to 250 °C, different NO2 concentrations and different time exposure. The sensor showed a p-type semiconducting behavior which probably owning to the strong effect of the hetero-junction between the n-WO3 nanoparticles and p-porous silicon substrate. The obtained results confirm the suitability of these structures to detect low NO2 concentrations up to 1 ppm at moderate temperatures. These sensors exhibit fast response and recovery times.