A complete description of the Supercritical Antisolvent Process requires the modeling of several complex phenomena such as heat and mass transfer, hydrodynamic, phase equilibria of ternary mixtures, and nucleation/growth of the specie to be precipitated. As a first step, we focus on the simulation of the heat and mass transfers of binary CO2-solvent mixture in miscible conditions, based on the pioneer work developed by Werling and Debenedetti. The system is described as a spot of pure solvent immersed in pure carbon dioxide, with a mass transfer ruled by diffusion. Various correlations for expressing the diffusion coefficients are discussed, and the Hayduck-Minhas is further selected for calculations; the incidence of the correlations on the droplet behaviour is also assessed. Compared to literature background, we investigate non-isothermal mixing, i.e. when temperatures of solvent and fluid are different. The evolution of the spot size is described for various conditions of pressure, temperature, temperature difference and for several CO2-mixtures frequently used in recrystallization. Results emphasize the role of temperature which can be an effective parameter to modulate the lifetimes of the droplets. In non-isothermal conditions, the immersion of a colder solvent in a warmer CO2 permits to increase the mixing time in an extend not attained by pressure or temperature in isothermal conditions; the reversed situation, e.g. a warmer solvent immersed in colder CO2, allows for speeding the mixing process. (C) 2010 Elsevier B.V. All rights reserved.