In this study, hydrogen gas sensing properties of nanoporous platinum films synthesized by using the dealloying method are investigated depending on annealing, temperature and gas concentration. Platinum – copper (Pt-Cu) alloy films with approximately 50nm are coated on microscope glass slide by using magnetron co-sputtering method. In order to obtain nanoporous Pt, Pt-Cu alloy films are dealloyed in 1 M nitric acid solution for different times (15 min, 30 min, 1 hour, 2 hours, 5 hours, 10 hours and 20 hours). The structural properties of Nanoporous Pt are characterized by XRD, SEM, EDS and XPS techniques. It is observed that when dealloyed in nitric acid solution for 5 hours, Cu was completely removed from the alloy and nanoporous Pt with regular pore structure was obtained. Nanoporous Pt, which is dealloyed for 5 hours, is heat treated at different temperatures from 200 °C to 500 °C. Resistive Nanoporous Pt sensors are examined in the concentration range of 30 ppm – 5% hydrogen. The results revealed that the hydrogen sensing mechanism of the Nanoporous Pt sensors could be explained with surface scattering phenomenon. The detailed hydrogen gas sensing properties of Nanoporous Pt sensor will be discussed depending on temperature, annealing temperature and gas concentration.