Abstract : The glucan composed of ? -(1?6) linkages with ? -(1?3) and ? -(1?4) branched linkages points was produced from Leuconostoc mesenteroides NRRL B-742. The glucan was hydrolysed by acid using microwave oven for production of gluco-oligosaccharides for time intervals of 2 min and 3 min and the optimum time period for oligosaccharide production was determined. The yield of oligosaccharides production from glucan was 2.5% for 2 min of hydrolysis time. The hydrolysed glucan was run on Sephadex G-10 column using FPLC and oligosaccharides produced were eluted and analyzed by MALDI Q-TOF mass spectrometer in MS/MS mode. The glucan sample hydrolysed by microwave for 2 min yielded the peak at ~527 m/z value showing the presence of 3 glucose units (m/z ~180) corresponding to the glucooligosaccharide with degree of polymerisation 3.