This thesis presents the fabrication, optimization, and characterization of Nb₂O₅ thin-film gas sensors for hydrogen detection, with a focus on the influence of film thickness, palladium (Pd) catalyst loading, and operating temperature on sensing performance. Nb₂O₅ thin films of 50 nm and 300 nm thickness were deposited onto alumina substrates equipped with platinum interdigitated electrodes using pulsed laser deposition (PLD) from a sintered niobium target, under a controlled oxygen atmosphere at approximately 20 Pa. Palladium catalytic overlayers were subsequently deposited by magnetron sputtering using a cumulative deposition approach enabling systematic investigation of catalyst thickness effects from 0.5 to 5 nm without sample-to-sample variability.