Isomaltooligosaccharides (IMOs) have wide applications as functional food ingredients, but their increasing demand has intensified the need to produce IMOs enriched with a specific oligosaccharide. In this study, the synthesis of high-panose IMOs catalyzed by the secondary transglycosylation activity of Cellulase DS (commercial enzyme preparation) was optimized using an overall desirability function, considering the initial maltose concentration (364–500 g/L) and enzyme-to-substrate (E/S) ratio (10–14 UT/g) as study variables according to a central composite rotatable design with three response variables (yield, specific productivity and overall selectivity for panose). Under the optimal conditions, a yield of 0.43 g/g, specific productivity of 0.28 × 10−2 g/UT.h and overall selectivity of 4.04 g/g were achieved at 11 h of reaction time when the initial maltose concentration and E/S ratio were set at 456 g/L and 10.6 UT/g, respectively. The overall selectivity was 29.9 % higher than that obtained with the commercial α-glucosidase Transglucosidase L 'Amano', and the panose composition was approximately 2.8 times that of the commercial formulation from FUJIFILM Wako Pure Chemical Co. The set of data obtained regarding the transglycosylation activity of Cellulase DS offers an attractive alternative for obtaining high-panose IMOs.