Selective recovery of platinum (Pt(IV)) from palladium (Pd(II))-containing hydrochloric acid (HCl) solutions was studied using 4-(hexyloxy) aniline hydrochloride (HOA). Pt was selectively and quantitatively recovered as precipitates at HCl concentrations of over 4M. Furthermore, the recovery of Pt was completed in just a few minutes. Since HOA was able to recover Pd as precipitates quantitatively at low HCl concentrations, the mutual separation of Pt and Pd was achieved by changing the concentration of HCl. X-ray photoelectron spectroscopy (XPS) measurements revealed the formation of ion-pairs composed of one metal chloro-complex anion ([PtCl6](2-) or [PdCl4](2-)) and two anilinium cations.