Extraction of U(VI) with high molecular mass carboxylic acids, viz., Versatic 10 and Versatic 911 (RH)(2) in benzene as diluent has been carried out as a function of equilibrium pH. The extracted species is found to be UO(2)R(2)(RH)(2). A comparison of pH(0.5) values for both the extractants shows that they are of comparable extraction efficiency. Synergism was obtained with the binary mixture of the extractants. Diluent effect on the extraction has also been carried out.