Nanostructured SnO2 with different morphologies of flower-like, sheet-like and granular have been successfully prepared via a solid-state reaction in the presence of NaBr, NaCl, and NaF, respectively. The added salts not only prevent a drastic increase in the size of the tin species but also provide suitable conditions for the oriented growth of primary nanoparticles. The formation mechanisms of these materials by solid-state reaction at ambient temperature are proposed. The gas sensitivity experiments have demonstrated that the as-synthesized SnO2 especially, flower-like morphology, exhibit high sensitivity to CO, which may offer potential applications in gas sensors. (C) 2008 Elsevier B.V. All rights reserved.