A study on the clarification of baker＇s yeast suspension by Colloidal Gas Aphrons (CGA) employing a cationic surfactant, benzyl-dimethyl-hexadecyl-ammonium chloride, is presented. The variables investigated were the CGA flowrate, air flowrate and the yeast concentration. A separation efficiency as high as 95% was achieved at the optimum conditions of air flowrate and feed concentration. The mechanism of particle-bubble attachment was identified and a simple model for the monolayer adsorption of yeast cells on the bubble surface derived.