Undoped and 0.2-1.0 mol% Rh-doped SnO₂nanofibers were fabricated using electrospinning combined with calcination treatment. The fibrous morphology of these nanofibers were maintained and the grain size of the SnO₂nanocrystals were greatly decreased after Rh doping. Sensors based on these nanofibers were fabricated through a hot pressing mathod. The gas sensing properties of these nanofibers were investigated systematically. The results indicated that the response to 50 ppm acetone of 0.5 mol% Rh doped SnO₂nanofibers was 60.6, which was 9.6 times higher than that of undoped SnO₂nanofibers. In addition, the Rh-doped SnO₂nanofibers showed a decreased cross-response to ethanol, whereas pure SnO₂naofibers did not show selective detection of ethanol and acetone gases. The doping of Rh ions into SnO₂nanocrystals modulates the electron concentration, and induces the changes of the oxygen vacancies and chemisorbed oxygen of SnO₂naofibers. Thus, the doping of Rh³⁺into SnO₂nanofibers should be a promising method for designing and fabricating acetone gas sensor with high gas sensing performance.