The present study investigates the growth kinetics of SnO2 nanograins and determines the activation energy and mechanism of the growth in nanofiber form. The activation energy for the growth of the SnO2 nanograins was estimated to be similar to 28.28 kJ/mol, which is an order of magnitude smaller than that of bulk SnO2. The estimated m value suggests that the growth mechanism of the nanograins is primarily through lattice diffusion in the pore control scheme. Precise control of the calcination temperature and time is necessary to maximize the efficiency of electrospinning-synthesized SnO2 nanofibers for sensor applications. Importantly, the sensor fabricated with nanofibers of small nanograins showed much better sensing properties to CO and NO2 comparing with the sensor fabricated with nanofibers of large nanograins. A mechanism to explain this finding is suggested. (C) 2010 Elsevier B.V. All rights reserved.