H2S gas sensors were fabricated using Ag nanowire/hollow polypyrrole nanotube nanocomposite (Ag NW/hollow PPy NT) film for sensing ppb-level H2S gas at room temperature. The morphology, phase composition and crystalline structure of Ag NW/hollow PPy NT nanocomposites were analyzed via scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffractometry (XRD) and Fourier-transform infrared spectroscopy (FTIR). TEM and SEM images revealed that Ag NWs were well dispersed in the hollow PPy NT matrix. IR results showed no interaction between Ag NWs and hollow PPy NTs in the Ag NW/hollow PPy NT nanocomposites. The effect of the amount of added Ag NWs on the response of the Ag NW/hollow PPy NT nanocomposites to the ppb-level H2S gas was investigated. Comparative gas-sensing results revealed that the introduction of Ag NWs onto hollow PPy NTs was effective in promoting the sensor response to H2S gas. More importantly, the Ag NW/hollow PPy NT nanocomposite had a strong response to ppb-level H2S gas at room temperature.