Fabrication of tin dioxide/polyaniline (SnO2/PANI) composite nanofibers by electrospinning technique for hydrogen gas sensing at low temperature is reported. Usually, nanofibers of pure or doped metal-oxide as gas sensor require high operating temperature more than 200 A degrees C. Fourier transform infrared (FTIR) and ultraviolet visible (UV-VIS) spectral analysis of as-prepared SnO2/PANI composite nanofibers revealed the incorporation of SnO2 in PANI matrix. Scanning electron micrographs (SEM) showed the increased in diameter of SnO2/PANI composite nanofibers as compared to that of pristine SnO2 nanofibers of average diameter of 200 nm, indicated the encapsulation of PANI on the surface of SnO2 nanocrystallites. The presence of tetragonal and crystalline structure of SnO2 in as-prepared SnO2/PANI composite nanofibers was not affected with the incorporation of PANI as confirmed from X-ray diffraction (XRD) pattern. Compared with the pristine SnO2 nanofibers, the SnO2/PANI composite nanofibers showed improved hydrogen gas sensing nearly at room temperature. The proposed sensing mechanism was systematically co-related to the existence of p-n heterojunction in SnO2/PANI hybrid material.