We present some results of experimental investigation into the process of formation of the condensation aerosol from non-saturated styrene vapor in plasma of a pulsed corona discharge. It is shown that the characteristics of thus generated aerosol depend on the parameters of the discharge and the type of the carrier gas. The characteristic values of the aerosol particle number density and the volume median particle radius vary within respectively 107-108 cm-3 and 0.05-0.3 mm. We propose a model for the process of aerosol generation from the unsaturated vapor.