Abstract: Conditions of the solvent floatation of p-hydroxybenzoic acid,in cluding the pH and ionic strength of the solution,the rate of air-flow,time of floatation and the ratio of volume of the aqueous and organic solvent phase,and the efficiency of different kinds of organic solvents for the floatation process were studied and optimized.A study on the kinetic mechanism was also performed and it was found that the solvent floutation process followed the first kinetic equation,and that the apparent rate constant increases with the increase of rate of air-flow.