Various thioglycosides 1 are smoothly hydrolyzed chemo-selectively to the corresponding 1-hydroxy sugars 2 in good yields at 0-5 degreesC by employing (NH4)(6)Mo7O24.H2O-H2O2 or H2MoO4.H2O-H2O2 to promote oxidation of ammonium bromide in the presence of perchloric acid in CH2Cl2-H2O solvent system. Mild conditions, good yields, no side reactions such as bromination either at the anomeric position or double bond, and even oxidation at the sulfur are some of the major advantages.