Hydrogen has been attracting much interest recently as a source of clean and sustainable energy. However, the volatility of hydrogen, its tendency to explode at concentrations as low as 4 % in air, requires a reliable sensing technology for safe hydrogen utilization. An optical hydrogen safety sensor based on gasochromic thin films can detect a change in color of the film upon exposure to hydrogen gas in an area where a hydrogen leak is suspected. In this study, we compared the sensitivity and the durability of hydrogen sensor films of Pd/WO3, Pt/WO3, and Pt/Pd/WO3. The change in the optical transmittance of the films was measured as these films were repeatedly exposed to hydrogen and air.