A study is reported of the value of ruthenium tetroxide as an oxidant in carbohydrate chemistry. It has been shown that partially benzoylated, benzylidenated, or isopropylidenated methyl glycosides are converted into protected methyl glycopyranosiduloses by the reagent. Ruthenium tetroxide also oxidises furanoid derivatives. A conversion of D-glucose into D-allose has been achieved by sequential acetonation, oxidation, reduction, and deacetonation. The glycopyranosiduloses derivable from methyl 4,6-O-benzylidene-2-deoxy-α-D-lyxo-hexopyranoside and methyl 3,4,6-tri-O-benzoyl-α-D-glucopyranoside have been found to undergo facile eliminations to give enones for which structures are elucidated. Brief comment is made on some experiments in which lead tetra-acetate was used as the oxidant for the preparation of protected methyl glycopyranosiduloses.