Abstract: A metal extraction process in which an aqueous leach solution containing metal values is contacted with a solution, in a water-immiscible organic solvent, of an extracting agent where the aqueous leach solution contains a wetting agent in a concentration of not more than 0.1% by weight. Wetting agents which may be used include alkoxylated alcohols or phenols, especially alcohols condensed with both ethylene oxide and propylene oxide, and ethylene oxide/propylene oxide/ethylene oxide block copolymers. The wetting agent can be present at a concentration of 0.00001% w/v or less. The presence of the wetting agent may reduce the build up of solid as crud and/or may reduce entrainment of one phase in the other.