A process for the separation of tungsten and molybdenum by extraction involves the addition to an aqueous solution containing tungsten and molybdenum nitric or hydrochloric acid to obtain a pH from 0.5 to 4.3, introduction of a stabilizer comprising water-soluble phosphorus salts and a complexing agent - hydrogen peroxide in an amount from 1.5 to 2 mol per 1 g-atom of the total content of tungsten and molybdenum. Then molybdenum is selectively extracted from the resulting aqueous solution with tri-n-butylphosphate with equal volumetric proportioning of the aqueous and organic solutions. Re-extraction of molybdenum and partially tungsten is carried out from the organic extracting agent with an alkali or soda solution.The process makes possible the preparation of tungsten solution containing no more than 0.001 g/l of molybdenum, and an increase in the degree of extraction of tungsten and molybdenum.