The context of the study is the Supercritical Antisolvent Process which required as a first step to investigate the disintegration of the injected solvent. In this paper, we focus on the simulation of the jet breakup in biphasic conditions, i.e. when the solution is injected into CO2 under conditions below the mixture critical point where liquid and vapor phases coexist. Simulations are carried out under various conditions of pressure and solvent in order to modify significantly the properties known to influence the jet breakup such as density, viscosity and surface tension. Numerical results reveal that in the range of investigated Reynolds and Ohnesorge numbers, the classical criteria used to distinguish the different modes of jet breakup at atmospheric pressure seems to be valid for the high pressure environment, agreeing thus the experimental results reported in literature. Pressure effects are emphasized in this work and we show that simulations are able to represent that a modification of pressure allows for changing the jet breakup mode, especially near the mixture critical point. Furthermore, a relationship is proposed to estimate the jet breakup length as a function of the Weber number of the liquid phase. (C) 2012 Elsevier B.V. All rights reserved.