The permeation of gold(I), as Au(CN)(2)(-), through supported liquid membrane (LM) impregnated with LIX 79 (guanidine derivative) in cumene has been studied. A model is reported describing the transport mechanism which consists of (a) diffusion process through the feed aqueous diffusion layer, (b) fast interfacial chemical reaction and (c) diffusion through the membrane, The mathematical equations describing the rate of permeation are derived to correlate the membrane permeability coefficient with diffusional and equilibrium parameters. The mass transfer coefficient was calculated from the described model as 5.5 x 10(-3) cm s(-1), and the thickness of the aqueous boundary was later calculated to be 1.3 x 10(-3) cm, Good separation against various metallic-cyano complexes was also obtained.