Possibility of preparing nanosize SnO2 particles from alkyl metal by pyrolysis was tested. SnO2 particles with a diameter of 10 to 45 nm were obtained from tetra-n-butyl tin (TNBT) in a tubular aerosol reactor. Crystalline SnO2 particles began to be formed over 500 degrees C. The size of SnO2 particles was increased with increasing concentration of precursor and decreasing reaction temperature. The number density in the reactor was in the order of 10(14)/ml. IR spectrum showed that the alkyl group was completely removed and the color became bright white as the reaction temperature was increased. Oxygen concentration was found to be around 80% for complete removal of alkyl group.