To understand the phase behavior of polyvinyl alcohol (PVA) in supercritical and subcritical fluids, the solubility in supercritical carbon dioxide (SCCO2) and subcritical 1,1,1,2-tetrafluoroethane (sub-R134a) was determined for a couple of PVA which differ in their molecular weights. At temperatures of 313, 323 and 333K, the solubility of PVA was measured in SCCO2 with the dynamic method in the pressure range of 9.0-18.0 MPa and in sub-R134a with the static method from 7.0 to 15.0 MPa. The solubility parameters (delta) of SCCO2 and sub-R134a at the experimental condition were calculated with Huang's equation of state and Giddings's equation, respectively. The effects of pressure, temperature, solute molecular weight, and solvent type on solute solubility were analyzed from the view of solvent density, solvent polarity, interaction between solvent and solute, solubility enhancement factor (SE), and solubility parameter. Five semi-empirical models (Chrastil, K-J, M-S-T, S-S, and Bartle models) were used to correlate the solubility data of PVA in SCCO2 and sub-R134a, and satisfactory correlation results were obtained. (C) 2015 Elsevier B.V. All rights reserved.