The synthesis of newO-β-D-glucopyranosyl- andO-β-D-galactopyranosyl-2-hydroxyacetaldehyde thiosemicarbazones (5a,b) is reported. Oxidation of allyl glycoside1with KMnO4followed by NaIO4cleavage of the resulting diol2afforded aldehyde3, which was then condensed with thiosemicarbazide and deprotected to give the target compounds (5a,b). Compounds5a,bshowed hydrolytic stability in neutral solution with half-life periods greater than 70 h. The SOD-mimetic activity was determined for the Cu(II) and Mn(II) complexes of5a,b(IC50= 0.2–0.8 mM). This activity is higher by two orders of magnitude than copper (II) bisthiosemicarbazones. The ESR and UV-Vis data of Cu(II)-5asuggest a tetrahedral distortion of the coordination sphere around the central copper atom which could be the reason for their high SOD-mimetic activity.