Mesoporous tin oxide (SnO2) spheres with a size of 500–700 nm have been successfully synthesized through annealing a tin hydroxide precursor was obtained by a one-pot solvothermal process from a methanol system containing the surfactant polyvinyl pyrrolidone (PVP). Experimental studies revealed that polyvinyl pyrrolidone plays a pivotal role in controlling the size and agglomeration of mesoporous spheres. The mesoporous SnO2 spheres with a surface area of 78.2 m2 g–1 and an average pore size of ca. 10 nm are monodispersed and the mesoporous structure can be maintained even after annealing at 500 °C for 2 h in air. Gas sensing tests showed that the SnO2 mesoporous spheres exhibit high sensitivity to H2, enhanced response to CO and also fast response and recovery rates, suggesting potential application as an advanced gas sensing material.