Abstract: The effect of organic acids on the cloud points of Triton X-100 was related to the hydrophilicity and space structure of organic acids and solubilization position in the micell.The addition of straight chain monoacids made the cloud point of Triton X-100 system decrease.The longer the chain length of straight chain monoacids is,the stronger the effect on the cloud points is.The effect of the straight chain diacids on the decreasing of the Triton X-100 cloud points is weaker than that of the straight chain monoacid.And it made the cloud points of Triton X-100 system increase if the carbon number of acid nc<6,and decrease if nc≥6.The addition of acids with branch chain and acids substitute made the cloud points of Triton X-100 system decrease within a lesser range,because of their steric hindrance effect.

Key words: Cloud point, Triton X-100, Organic acid, Straight chain monoacid, Straight chain diacid