In this study, we report phase behavior data for propylene + toluene and ethylene + toluene mixtures at temperatures to 580 K and pressures to 8.5 MPa. We also report high-pressure, mixture density data for the two mixtures at temperatures to 555 K and pressures to 70 MPa. Both the phase behavior and density data are simultaneously determined using a windowed variable-volume, high-pressure view cell coupled with a linear variable differential transformer. The phase behavior and mixture density data are modeled with the Soave-Redlich-Kwong (SRK), Peng-Robinson (PR), Modified Sanchez-Lacombe (MSL), and Perturbed-Chain Statistical Associating Fluid Theory (PC-SAFT) equations of state (EoS). The PC-SAFT and MSL EoS provide very good fits of the phase behavior for both the propylene + toluene and ethylene + toluene systems with each binary interaction parameter, k(ij), set to zero. The PC-SAFT equation also provides the best fit of the high-pressure, mixture density data for the ethylene + toluene system. However, the SRK EoS provides the best fit of the high-pressure, mixture density data for the propylene + toluene system. Although both equations slightly over predict the solution density for the two studied systems, the fit of the densities are insensitive to small variations in k(ij). (C) 2017 Elsevier B.V. All rights reserved.