Hydrolysis of the diterpene glycoside, rebaudioside M isolated from Stevia rebaudiana Bertoni was performed using acid and base conditions. Acid hydrolysis was carried out using H2SO4 and HCl, whereas base hydrolysis was performed using NaOH. This is the first report of the synthesis of isosteviol and rebaudioside B from the diterpene steviol glycoside rebaudiosides M. The structures of the acidic and basic hydrolysis products were achieved on the basis of extensive spectral data and literature comparison. Further, configuration of sugar moieties in the steviol glycoside rebaudioside M obtained during the course of acid hydrolysis studies and its base hydrolyzed product rebaudioside B were confirmed by preparing their corresponding thiocarbamoyl-thiazolidine carboxylate derivatives with L-cysteine methyl ester and O-tolyl isothiocyanate and in comparison of their retention times with standard sugars.