A novel application of the secondary atomization of precursor solution droplets is explored as a means of size control in the combustion aerosol synthesis of zirconia nanoparticles. In combustion aerosol synthesis, small precursor solution droplets are required to produce small uniformily sized nanoparticles. This study investigates the use of mixed hydrocarbon solvents to promote the fragmentation of precursor solution droplets for the production of nanoscale zirconia. By rapidly heating the droplets to the superheat limit temperature, explosive fragmentation is induced, reducing the size of the carrier droplets. Results indicate that when mixtures of hexadecane with propanol or butanol are used for precursor delivery, the sprayed droplets undergo fragmentation in the high-temperature region of a flame reactor. Consequently, zirconia nanoparticles with a number mean electrical mobility diameter of 60 nm and relatively uniform sizes are produced. (C) 2003 Elsevier Ltd. All rights reserved.