Comparative studies on the extraction of Cu（Ⅱ） have been performed by 2-hydroxy-5-（1-methylheptyl） benzaldoxime （N-590） without or with n-dodecanol as modifier, 2-hydroxy-5- （1-metylheptyl） benzophenone oxime （N-510）, and 2-hydroxy-4-（1-methylheptyloxy） ben-zophenone oxime （N-530）. When the extraction is carried out in feed liquor containing Cu1.03 g/L and Fe 10.7 g/L by 0. 1 mol·dm-3 extractant in kerosene, the Cu percentage extrac- tion of 95.6, 89 and 63%, and Cu（Ⅱ）-Fe（Ⅲ） separation factor of 1.46×103, 4.76×102and 1.26×102 are obtained with N-590, N-530 and N-510, respectively; moreover the Cuextraction and stripping speed with N-590 is greatly higher than that with N-530 and N-510. Addition of 2% n-dodecanol into 0.1 mol·dm-3 N-590 in kerosene improved the strip-ping behaviour.
