To support the phaseout of high global warming potential working fluids commonly used in air-conditioning and refrigeration systems, detailed knowledge about the thermodynamic and transport properties of replacements, for example, hydrofluoroolefins (HFOs), in lubricant oils is required. In this context, isothermal experimental vapor-liquid equilibrium (PTx) and diffusivity measurements for 2,3,3,3-tetrafluoropropene (R-1234yf) and trans-1,3,3,3-tetrafluoropropene (R-1234ze (E)) in a synthetic polyol ester lubricant (ISO VG 32) were performed using a gravimetric microbalance over a temperature range from 248.15 to 348.15 K and pressures of up to 0.6 MPa. A nonrandom two liquid (NRTL) activity coefficient model was applied to correlate the measured solubility for each HFO/lubricant mixture. The diffusivities of R-1234yf and R-1234ze (E) in ISO VG 32 oil were determined from time-dependent absorption data based on a one-dimensional diffusion equation. The calculated diffusivities ranged from 10(-12) to 10(-10) m(-1) and were dependent on temperature and refrigerant composition.