The change of water droplets state is modelled numerically under various heat and mass transfer conditions during their unsteady evaporation. The modelling is performed using the method of combined analytic-numeric research of heat and mass transfer in a two-phase "droplets-gas" flow. The algorithm of an iterative research is constructed for the analytically obtained system of integral equations. Regularities of heat transfer process interaction are examined. The dependence of the droplet state change on its heating manner is determined. Unsteadiness and interaction of transfer processes, as well as selectivity of radiant absorption in water droplets are evaluated. It is indicated that cognition of the droplet state change regularities in the case of conductive heating is very important in determination of two-phase flow and in construction of an engineering research method. (c) 2005 Elsevier Ltd. All rights reserved.