Polarographic determination of uranium (VI) has been studied in the organic extraction phase TBP—diluent along with a selected aprotic solvent (i. e. dimethyl sulfoxide or N,N-dimethylformamide). DMF was found more suitable because it dissolves the organic extraction phase better than DMSO. U (VI) extracted in TBP-kerosene, n-hexane, cyclohexane, n-dodecane, benzene, from nitric acid medium can be determined in an organic solution (e. g. 50% DMF-30% TBP-20% kerosene) where it gives a well defined wave. In the organic solution, nitric acid added and/or extracted from the aqueous phase was found as an excellent supporting electrolyte for uranium determination.