This study describes the fractionation of soluble proteins from sweet white lupin, sweet yellow lupin, and bitter yellow lupin by thermal coagulation by heating at 50, 75 and 100°C. The thermal coagulation characteristics of protein are not influenced by alkaloid levels. They depend on the species and the pH of the solubilization medium. The solubility of white lupin proteins is the most sensitive of the three lupin cultivars to thermal treatment. The treatment can eliminate bitterness. The fractions thermocoagulated at 50, 75 and 100°C had different amino acid profiles for the three species, and all had lower hydrophilic/hydrophobic amino acid ratios than the residual soluble proteins after 100°C, particularly the two yellow species. SDS-PAGE showed gradual loss of large peptides (20-36 kDa) from the supernatant with increasing temperature. Thermocoagulation increased in-vitro digestibility and the water and oil retention of proteins, except for the water retention of the white lupin fraction coagulated at 50°C.