This paper first reports a highly reliable self-powered hydrogen (H-2) sensor employing a palladium (Pd)-based nano-transducer. The developed sensor is based on the principle of a novel chemomechanical mechanism of the Pd nano-transducer exploiting a solar cell. We theoretically and experimentally demonstrated that the proposed device can achieve highly durable operation for a wide range of H-2 concentrations with remarkable sensitivity (3.1% at 2%-H-2) and response time (111 s at 2%-H-2) without external power. Significantly, the proposed sensor, which has a novel sensing mechanism, maintains high sensing performance for more than 150 cycles under various H-2 conditions (0.5 to 2%).