A process for producing a conjugated di- or poly-unsaturated fatty acid having from 12 to 24 carbon atoms, or a salt or ester thereof, comprises: reacting a non-conjugated free fatty acid, or a salt or ester thereof, with a base in the presence of an alcoholic solvent comprising ethanol; and separating the conjugated fatty acid from the reaction mixture, wherein the separation of the conjugated fatty acid from the reaction mixture comprises contacting the reaction mixture with an aqueous salt solution and removing a liquid phase which comprises the salt solution and at least a part of the solvent from a solid phase which comprises a salt of the conjugated fatty acid.