The reduction of Cr V I by α-d-glucose and β-d-glucose was studied in dimethyl sulfoxide in the presence of pyridinium p-toluensulfonate, a medium where mutarotation is slower than the redox reaction. The two anomers reduce Cr V I by formation of an intermediate Cr V I ester precursor of the slow redox step. The equilibrium constant for the formation of the intermediate chromic ester and the rate of the redox steps are different for each anomer. α-d-Glucose forms the Cr V I -Glc ester with a higher equilibrium constant than β-d-glucose, but the electron transfer within this complex is slower than for the β anomer. The difference is attributed to the better chelating ability of the 1,2-cis-diolate moiety of the α anomer. The Cr V species, generated in the reaction mixture, reacts with the two anomers at a rate comparable with that of Cr V I . The EPR spectra show that the α anomer forms several linkage isomers of the five-coordinate Cr V bis-chelate, while β-d-glucose affords a mixture of six-coordinate Cr V mono-chelate and five-coordinate Cr V bis-chelate. The conversion of the Cr V mono- to bis-chelate is discussed in terms of the ability of the 1,2-cis- versus 1,2-trans-diolate moieties of the glucose anomers to bind Cr V .