New data of densities at temperatures in the 288.15-333.15 K range and several pressures, up to 40 MPa, have been measured for 2,2,2-trifluoroethanol + 1-butyl-3-methylimidazolium hexafluorophosphate system using a vibrating tube densimeter. The combined expanded uncertainty at the 0.95 confidence level in the density measurements is 2 kg.m(-3). Excess molar volumes, V-m(E), and apparent molar volumes, V-phi, were determined from the density values of the pure compounds and mixtures. The influence of the temperature, pressure and composition on V-m(E), V-phi, was studied. In general, the dependence of V-m(E) with the mole fraction is sigmoid showing that there is a competition between the breaking and formation of interactions and the packing effect; V-phi was represented using the Redlich-Mayer equation, indicating that hydrogen bonding interactions are inexistent or scarce. Derived properties, K-T and alpha(p) were calculated from the analytical differentiation of the Tait equation, and it was observed that the variation with pressure and temperature is very small for 1-butyl-3-methylimidazolium hexafluorophosphate. In addition, PC-SAFT parameters of 1-butyl-3-methylimidazolium hexafluorophosphate were optimized using density data at atmospheric pressure. From PC-SAFT, pVT behaviour was reasonably well predicted with an average relative deviation of 3.1%, whereas sigmoid behaviour of excess molar volumes is not represented by the model. (C) 2017 Elsevier Ltd.