Modeling of chemical and phase equilibria of alpha-pinene hydration in subcritical CO2 was carried out by calculation. A simplified scheme of the conversion includes 6 reaction routes. Thermochemical and physicochemical parameters of individual compounds (T-cr, P-cr, T-b, Delta H-f degrees (298.15 K), Delta S-f degrees (298.15 K), C-p (T), omega) were preliminary estimated. Phase diagrams of the model reaction mixtures were calculated, coordinates of the critical point were found, and the region of subcritical parameters T and P, where the initial mixture divides into the gas phase and CO2-expanded liquid, was located. Dependence of the products distribution and yield of CO2-expanded liquid on the reaction temperature and pressure was studied. The reaction equilibrium as a function of temperature and pressure was determined, and heat effects of all reactions under consideration were calculated. The drift of critical parameters versus reaction mixture composition was examined. It was shown that during the hydration and alcohols accumulation the critical pressure of reaction mixture increases continuously, the critical temperature at first elevates and then begins to decrease, and the phase diagrams starts to degenerate. If amount of alcohols becomes more than 80 mol%, the mixture has no critical point and cannot pass to a supercritical state. (C) 2009 Elsevier B.V. All rights reserved.