Nitrile groups have strong polarity and show the non-ideal phase equilibria. Phase equilibria for the 3-phenyl propionitrile and 2-phenyl butyronitrile play an important role as organic solvents in several industrial processes. The solubility curves of binary mixture for 3-phenyl propionitrile and 2-phenyl butyronitrile in supercritical CO2 are investigated using a synthetic method at five temperatures of (313.2, 333.2, 353.2, 373.2 and 393.2)K and pressure up to 34.45 MPa. Both CO2 + 3-phenyl propionitrile and CO2 + 2-phenyl butyronitrile systems have critical mixture curves that show maximums in pressure temperature space between the critical temperatures of CO2 and 3-phenyl propionitrile or 2-phenyl butyronitrile. The solubility of CO2 for two systems at a constant pressure decreases with the increase of temperature. The CO2 + 3-phenyl propionitrile and CO2 + 2-phenyl butyronitrile systems display type-I phase behavior within scope of this work. The experimental results for the CO2 + 3-phenyl propionitrile and CO2 + 2-phenyl butyronitrile binary systems are correlated with Peng-Robinson equation of state using a mixing rule including two adjustable parameters (k(ij) eta(ij),). The critical properties (pc, Tc and omega) and vapor pressure of 3-phenyl propionitrile and 2-phenyl butyronitrile were estimated with the joback-Lyderson group contribution and Lee-Kesler method. (C) 2016 Elsevier B.V. All rights reserved.