Diisododecylamine (DIDA) is shown to be an efficient agent for extracting vanadium(V) ions from weakly acidic (pH 5–6) sulfuric acid media. Its parameters are comparable with those for vanadium extraction by the well-known amine extracting agent TOA (tri-n-octylamine). The extraction of vanadium(V) ions by DIDA from the real shop leach liquors of vanadium slag with a vanadium concentration of 3.13–5.08 g/l is tested under laboratory conditions using the results obtained. Vanadium is reextracted from the organic phase by solutions of ammonia water (1: 1). The V2O5 samples prepared by the extraction technology are shown to satisfy the specifications of pure VnO-1 vanadium pentoxide.