Cottonseed, sesame, soybean and safflower oils were partially hydrogenated under selective condi-tions using Rufert nickel catalyst. Samples drawn at intervals were subjected to pancreatic lipase hydroly-sis, and the positional distribution of fatty acids was determined. Results indicate preferential hydrogena-tion of linoleic acid present in the 1,3-position over that present in the 2-position of the triacylgly-cerols.