The results of experimental and computational investigation of evaporative cooling of micron-sized droplets in a low-pressure aerosol reactor (LPAR) are reported. The cooling rate of the aerosol was found to be about 2 x 10(3) K/s. A constant low pressure, the flow rates of the carrier gas and solution are major factors that affect droplet cooling. A higher total pressure accelerated the change in droplet radius. For some regimes it was predicted that an aerosol undergoes freezing and then melting. The characteristic time required for evaporative cooling is about 1 ms. The agreement between experimental results and calculated values, based on the free molecular approximation of heat and mass transfer processes, is reasonably good. (c) 2006 Elsevier Ltd. All rights reserved.