The liquid-liquid equilibria (LLE) for the dextran T500 (DEX T500) + poly(ethylene glycol) 20000 (PEG20000) + water aqueous two-phase system were measured at 20 degrees C. Furthermore, the molecular weight distributions of DEX and PEG in the top and bottom phases were measured. The partition coefficients (K-p) of hydrolytic enzymes, alpha-amylase, beta-amylase and glucoamylase were also measured. LLE and K-p were correlated using a modified Flory-Huggins equation developed for aqueous systems. The molecular weight distribution of DEX was expressed by a Gamma distribution function. LLE and molecular weight distributions were correlated successfully using a continuous thermodynamic approach. The partition coefficients were also correlated with good agreement.