SummaryA method has been developed for utilizing low‐cost acidulated refinery soapstock directly as raw material for producing the mixed methyl esters of cottonseed oil fatty acids. The conditions determined as optimum for producing the esters were as follows: temperature, 110°C. to 120°C.; pressure, 150 p.s.i.g.; reaction time, 10 to 15 min.; catalyst, acidic, proportioned as 3% to 5% of the fatty acids of the foots; and ratio of reactants, 5 moles of methanol to 1 of fatty acids.Processing acidulated foots containing 12.4% of neutral oil at the foregoing conditions resulted in esterifying 83% to 86% of the fatty acids. Reprocessing the same material after dehydrating it and restoring the initial methanol to fatty acids ratio increased the percentage of fatty acids esterified by about 5%.