The production of cyclodextrins (CDs) by cyclodextrin glycosyltransferase (CGTase) from Bacillus clarkii 7364 was studied. Forty-seven percent (w/w) conversion rate to gamma-CD was obtained in the process performed by reacting 5 U per gram of starch CGTase with 15 % (w/v) soluble starch in 0.025 M sodium phosphate-NaOH buffer (pH 12) at 55 A degrees C in the presence of 2 % (w/v) glycyrrhizic acid. Meanwhile, the ratio of gamma:beta-CD was 89:11, with negligible formation of alpha-CD. Under these conditions, there is a significant increase in overall production of CDs and a marked change in product selectivity for gamma-CD. The possible mechanisms were discussed upon different product profiles with respect to the size and amount of CDs synthesized at different reaction conditions. The approach described here can be easily applied to an enzymatic process for the production of gamma-CD on an industrial scale, and such high selectivity, at high conversions, is especially attractive from a commercial perspective.