Vapour-liquid, liquid-liquid and liquid-liquid-vapour equilibria for the system 1,1,1,2-tetrafluoroethane + phenyloctane were determined in the temperature range from 260 to 400 K and at pressures upto 12 MPa. The system was found to be a type IV system according to the classification of Van Konynenburg and Scott. The (l(2) = l(1))g upper critical endpoint of the low-temperature branch of the l(2)l(1)g curve was found at T = 352.85 K and P = 2.440 MPa. The (l(2) = l(1))g lower critical endpoint of the high temperature branch of the l(2)l(1)g curve was found at T = 381.82 K and P = 4.220 MPa and the upper critical endpoint l(2)(l(1) = g) at T = 392.88 K and P = 5.135 Wa. (C) 2004 Elsevier B.V. All rights reserved.