According to the method of Rapaport-Weinstock an aerosol generator was constructed with a joint vapour and nuclei source. The generator is ready for operation after a few minutes, and the modal diameter of the aerosol size distribution can be changed in the same time. Theoretical considerations for the best operating conditions of the generator are given. Experimental results show the dependence of the particle size distribution on the different operating parameters. The number concentration of the produced aerosol is more than 106 cm-3, the geometric standard deviation less than 1.10, and the particle diameter is varied between 0.2 and 2 μm, but this range can be extended.