SnO 2 nanoparticles were successfully synthesized by a novel one-pot route using two various Sn salts of SnCl 4 ·5H 2 O and SnCl 2 ·2H 2 O as raw materials, respectively. The thermogravimetric-differential scanning calorimeter (TG-DSC), X-ray diffraction (XRD), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED) and gas sensitivity measurement were characterized to determine the influences of salt type and calcination temperature on the thermal effect, crystal structure, crystallite size and gas sensitivity of SnO 2 nanoparticles. Results indicated that the two series of samples had different crystallization process, crystallite size and gas sensitivity changed with calcination temperature. SnCl 4 ·5H 2 O helped to promote crystallization, but SnCl 2 ·2H 2 O suppressed the crystallization and crystallite growth even at the same calcination temperature. SnO 2 nanoparticles calcined at 500 °C using SnCl 4 ·5H 2 O and 250 °C using SnCl 2 ·2H 2 O displayed better gas sensitivity because of high crystallinity and small crystallite size, possibly decreasing the number of boundary defects which can cause electron recombination as well as providing more reaction cites, respectively.