Tungsten oxide thin films with a suitable catalyst coating such as Pd or Pt are extensively used in fabrication of hydrogen optical sensors based on gasochromic property. In these sensors the dissociation of H 2 molecules on the catalyst surface and subsequent injection of proton-electron into WO 3 structure leads to optical alteration of WO 3 layer. The efficiency and durability of Pd/WO 3 sensors directly depend on the number of catalyst atoms. However, the adsorption of contaminated species like CO on the catalyst surface known as catalyst poisoning decreases the number of available sites for hydrogen dissociation resulting in destructive effects on gasochromic response. On the other hand, anatase titanium oxide is a capable semiconductor to break down the surface contaminations due to its photocatalytic property. Therefore, fabricating of TiO 2 /WO 3 thin films may be a new approach to eliminate catalyst poisoning in hydrogen optical sensors. The required temperature for anatase TiO 2 formation is 400-600 ?C which in turn causes WO 3 crystallization, hence poor gasochromic response. So, modern laser annealing technique was utilized in order to form anatase TiO 2 . In this regared, pulsed laser deposited TiO 2 /WO 3 thin films were exposed to single pulse of excimer laser with different energies. Our findings show that anatase TiO 2 structure forms at 110 mj energy. Increasing laser energy leads to crystallization of monoclinic WO 3 . Furthermore, morphology and elements distribution in our samples change after laser irradiation. Laser annealing reduces optical transmittance and band gap of TiO 2 /WO 3 thin films too. Water contact angle measurments confirm enhanced hydrophilicity after laser treatment. Moreover, laser irradiated samples at 110 mj and 170 mj have the best photocatalytic and gasochromic activities respectively.