Sarcosine and sorbitol at 10-30% (w/w) stabilized haemoglobin from human erythrocytes to thermal denaturation. At 65 degrees C, the protein＇s half life was increased from 0.85 to 50 min in 30% sarcosine and to 24 min in 30% sorbitol. A kinetic analysis based on the Lumry-Eyring mechanism of inactivation showed that the denaturation process can be described by a second-order rate expression with an apparent activation energy ranging from 56 to 87 kcal mol(-1).