The oxygen solubility coefficient (αO2) of several different physiological saline solutions was measured over a broad range of temperatures (0 to 25‡C). Distilled water had a higher value than a physiological salt solution (similar to Cortland's saline). Plasma expanders (polyvinylpyrrolidone, dextran, albumin) lowered the αO2 value of the physiological salt solution. A salt solution with a 4% (w/v) mixture of protein substitute had a lower αO2 value than the corresponding 1% mixture. The solubility of oxygen was inversely related to temperature.