Porous SnO₂ nanospheres with high surface areas have been synthesized through a solvothermal method in the absence of any templates. The structure and morphology of the resultant products were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and nitrogen adsorption–desorption technique. The as-prepared SnO₂ porous nanospheres with the diameters ranging from 90–150 nm are composed of small nanocrystals with average sizes of less than 10 nm. Results demonstrated that the formation of porous SnO₂ nanospheres is ascribed to etching the center part of the nanospheres. It was found that hydrochloric acid and NaClO played important roles in determining the final morphologies of the porous SnO₂ nanospheres. The gas sensing properties of the as-prepared porous SnO₂ nanospheres were investigated. By the comparative gas sensing tests, the porous SnO₂ nanospheres exhibited a superior gas sensing performance toward ppb level 2-chloroethanol and formaldehyde vapor, implying promising applications in detecting toxic volatile organic compounds (VOCs).