The mechanism of vaporization of a liquid metal drop in the crucible-free method for the production of aerosol particles was investigated. By using different metals (such as Ni and Cd) it was established that during vaporization in an inert gas flow, the liquid metal drop becomes partially hollow. Evaporation of metal atoms from the inner cavity of the drop is more intense as compared to that from the surface. The process is followed by the condensation of small metal particles. The aerosol particles obtained by these routes differ in their size distribution. A scheme of the processes under study is suggested.