In this study, hydrogen was sensed on Pt/C/Nafion composite electrodes prepared by a hot-pressed method. The results reveal that the sensitivity of the electrode increases with an increase of Pt loading. At a Pt loading of 3.0 mg/cm(2), the sensitivities of the electrodes treated by direct wetting and indirect wetting methods are 0.263 and 0.716 muA/ppm, respectively, in the H-2 concentration range of 1260-5250 ppm. This indicates that indirect wetting is a better method for moistening the hydrophobic electrode. Generally, both the response time and the recovery time decrease with increasing both the hydrogen concentration and the Pt loading. The electrode prepared in this study has the advantage of a higher catalytic surface area, which results in a sensitivity 50 times higher than that of electrodes prepared by other methods at the same Pt loading. Meanwhile, a sensing model is proposed to illustrate the sensing phenomenon.