Fluid-liquid (FL) pressure and fluid-solid (FS) temperature of poly(ethylene-co-hexene-1) (EH) in sub- and supercritical propane and ethylene + hexene-l mixtures are measured with a variable-volume batch optical cell. The effects of the EH concentration, weight-averaged molecular weight (M-w), branch density (BD), crystallizability, solvent type, and solvent ratio on the phase behavior are investigated at temperatures up to 180 degrees C and at pressures up to 1400 bar. Both EH concentration and M-w are found to have a relatively weak effect on the phase behavior. The FL pressure and FS temperature are found to decrease as ED increases. The FL pressure is also found to depend strongly on the solvent type. When the ethylene concentration increases in ER + ethylene + hexene-l mixtures, the FL pressure is found to increase, whereas the FS temperature is found to decrease.