Using a pilot scale mixer-settler, a solvent extraction study was carried out on the extraction of tantalum and niobium with TBP(tributyl phosphate)as a solvent from the HF-H₂SO₄-H₂O system. The concentration of sulfuric acid in the feed solution was found to affect not only extraction yield of tantalum and niobium but also extraction behavior of the impurities. The experimental conditions were established to achieve a yield higher than 99% for the extraction of tantalum and niobium. To remove the impurities from the organic solution, serubbing experiments were performed; the scrubbing was found effective under the conditions that the concentration of sulfuric acid is 9N and the ratio of the volumetric flow rate of the organic feed to that of the aqueous feed into the mixer-settler is 5. In the striipping of niobium from the organic solution, the phase separation was much easier with 1N H₂SO₄ solution as a stripping medium than with water. finally, tantalum and niobium having a purity of 99.9%, respectively, were obtained using the pilot scale mixer-settler.