Crude tantalum is dissolved in an aqueous hydrofluoric acid containing solution to forr tantalum-fluorine complex anions which are then extracted into an organic solvent solution of a water-insoluble quaternary ammonium compound having great affinity for the tantalum anions. The organic solution is next washed with an aqueous solution containing an inorganic acid and/or an ammonium salt to remove impurities extracted with the tantalum. Tantalum hydroxide precipitated by subsequent treatment with aqueous ammonia is recovered and calcined to yield tantalum pentoxide having a purity of five or six nines.