Facilitated transport of Ni(II) ions across a supported liquid membrane (SLM) by dithiophosphonates dissolved in methanol as carrier has been investigated. In this work, the SLMs were composed of ionic ligands ammonium-O-ethyl (4-methoxyphenyl) dithiophosphonate (L1), ammonium-O-propyl (4-methoxyphenyl) dithiophosphonate (L2), ammonium-O-isopropyl (4-methoxyphenyl) dithiophosphonate (L3), and ammonium-O-butyl (4-methoxyphenyl) dithiophosphonate (L4) as the carriers.