Abstract: The solvent extraction of KAu(CN) 2 from alkaline solution by the tri n alkyl ammonium chloride (N263) using 198 Au tracer has been investigated. The effects of various parameters, such as gold (Ⅰ) concentration in aqueous phase, cosolvent, phase ratio on the extraction of gold (Ⅰ) are studied. The results demonstrate that almost all of gold (Ⅰ) in aqueous phase can be extracted into the organic phase. Water concentration decreases significantly with the increase of gold (Ⅰ) concentration in the organic phase. No water molecule could be involved in the extraction of gold (Ⅰ).