SummaryNodososide, a new anthraquinone glucoside isolated from the flowers ofCassia nodosa, has been determined quantitatively in amount ranging from 0.2 to 2.0μmoles by oxidation with 40μmoles of hexacyanoferrrate (III) in alkaline medium under reflux for 90–100 minutes at about 150°. The oxidation required 14 equivalence with the formation of 2,6-dihydroxytoluene, carbon dioxide (as Na2,CO3) and the sodium salts of formic, acetic, maleic and arabonic acids. The relative mean error, standard deviation and the relative mean deviation were calculated to be 0.85, 0.96 and 0.62 % respectively. A tentative stepwise mechanism has been proposed and the oxidation products were identified. The conditions of stoichiometric oxidation have also been studied.