An apparatus has been developed to produce submicron aerosols of zinc oxide by the condensation of supersaturated vapors in a tube furnace. The mass concentration and the size distribution of the aerosols were stable over a period of several hours. Various particle morphologies (chain aggregates, large blocky particles and fine spiked particles) were produced by varying the operating conditions. According to analyses of electron micrographs, the primary particle diameters obeyed a log-normal distribution with count median diameters between 0.008 and 0.040 µm with geometric standard deviations from 1.42 to 1.67.