Extraction of U/VI/ by mixtures of 8-hydroxy quinoline /Oxine/ and neutral donors was studied from 0.1M NaCl at a pH 4.5. The presence of a neutral donor enhanced the extraction of U/VI/ and the species responsible for synergism was established to be 11 adduct UO2Ox2S. From the data, the equilibrium constants for the adduct formation reaction were calculated and was found to be the lowest with TBP and the highest with TOPO.