The extraction of gold(I) from aurocyanide aqueous solutions using EM 79 has been studied. Different variables that could affect the extraction system were evaluated: equilibration time, aqueous pH, metal and extractant concentrations, organic phase diluent and aqueous ionic strength. The extraction of the aurocyanide complex with respect to other metal-cyano complexes has also been studied on both synthetic and real leach solutions. Gold experimental data have been analysed numerically to determine the stoichiometry of extracted species and its equilibrium constant. It was found that gold(I) was extracted into the organic phase by the formation of the species RHAu(CN)(2) (LIX 79 = R). Stripping of gold from loaded organic phases was carried out using NaOH or NaCN solutions.