The influence of aqueous phase pH on the rate of liquid-liquid extraction was investigated, using single drop experiments for a range of drop size and in either of the mass transfer directions. The chemical system of toluene-acetone-water was employed with the advantage of high accuracy and repeatability when analyzed with gas chromatography. The pH of continuous aqueous phase was adjusted within 5.5-8, a range in which most industrial waters are lain. An extraction column was used to introduce the drops into the aqueous phase. Results have demonstrated the impact of pH on the mass transfer performance giving a significant reduction in mass transfer with increasing pH and nearly independent of the kind of accompanied cation for two utilized bases. This matter can be attributed to the adsorption of hydroxyl ions from the aqueous phase which causes small drops to be more prone to this effect. The rate of mass transfer is greater for the dispersed to continuous phase direction under similar conditions.