This work reports phase equilibrium data of pressurized (propane + L,L-lactide) system at different ethanol to monomer mole ratios (9: 1; 7: 1; 5: 1). Phase equilibrium experiments were accomplished in a high-pressure variable-volume view cell employing the static synthetic method. (Vapour + liquid) equilibrium data for the pseudo-binary systems were determined within the temperature range from (323 to 353) K and pressures up to 3.3 MPa. For the systems investigated, (vapour + liquid) equilibrium (VLE) was visually recorded. It was observed that an increase in temperature or in propane concentration led to a pronounced rise in pressure transition values. On the other hand, an increase in the ethanol to L,L-lactide mole ratio led to a reduction in pressure transitions, whereas a reduction in ethanol concentration complicates the achievement of one-phase homogeneous system. Thus, rapid complete miscibility of the system can be controlled by the amount of ethanol added as a co-solvent. The experimental results were modelled using the Peng-Robinson (PR) equation of state with the Wong-Sandler (PR-WS) mixing rule, providing a good representation of the experimental phase transition points. (C) 2014 Elsevier Ltd. All rights reserved.