Sophorolipids (SLs) were produced from Candida bombicola using soy molasses and oleic acid as co-substrates. The purified SLs were obtained at 21 g l(-1) and were 97% in lactone form. The major SL constituent (81% relative abundance) of the product mixture contains an oleoyl chain. The surface properties of the SLs obtained from the soy molasses/oleic acid fermentation had minimum surface-tension values of 37 mN m(-1) ( pH 6) and 38 mN m(-1) (pH 9), and critical micelle concentration values of 6 mg l(-1) (pH 6) and 13 mg l(-1) (pH 9).