A hydrogen gas sensor based on palladium-tin oxide-molybdenum disulfide (Pd-SnO2/MoS2) ternary hybrid was fabricated. Excellent sensing properties of the Pd-SnO2/MoS2 film sensor toward hydrogen were demonstrated at room temperature. The sensing mechanism of the sensor attributed to the synergistic effect of the ternary nanostructures and potential barrier modulation was discussed.