A dual functional sensor for detecting both UV light and H 2S gas was fabricated using the hexagonal phase porous In 2O 3 nanoparticles, which were prepared using the hydrothermal and calcination process. The porous In 2O 3 nanoparticles with large surface areas and pore volumes could provide plenty of active sites to produce much active oxygen species, which were beneficial for the UV light and H 2S gas sensing reactions, thus resulting in a good sensing performance. At room temperature, the dual functional sensor based on porous In 2O 3 nanoparticles exhibited ultra-high responses for sensing both UV light (with a wavelength of 365 nm) and H 2S gas. As a UV sensor, its response was 12886.0 for a UV power intensity of 1.287 mW/cm 2 and its detection limit was 0.013 mW/cm 2. As a H 2S gas sensor, the sensor exhibited an ultra-high response (26268.5–1 ppm H 2S) and a very low detection limit (1 ppb of H 2S), and it also have excellent selectivity, reversibility and stability.