The one-electron reduction of nitrite (NO 2 − ) to nitric oxide (NO) and ene-diol oxidation are two important biochemical transformations. Employing mononuclear cobalt-nitrite complexes with Co III and Co II oxidation states, [(Bz 3 Tren)Co III (nitrite) 2 ](ClO 4 ) (1) and [(Bz 3 Tren)Co II (nitrite)](ClO 4 ) (2), this report illustrates NO release coupled to stepwise oxidation of ene-diol antioxidants such as L-ascorbic acid (AH 2 ) and catechol. Analysis of the AH 2 end-product reveals that the reaction with complex 1 affords dehydroascorbic acid. Intriguingly, a controlled oxidation of AH 2 with complex 2 results in a [Co II ]-bound ascorbyl radical-anion (8). Finally, NO release with the concomitant generation of metal-bound 3,5-di-tert-butyl-semiquinone radical anion from the reactions of 3,5-di-tert-butyl-catechol and [(Bz 3 Tren)-M II (nitrite)](ClO 4 ) (2, M = Co; 4, M = Zn) provides mechanistic insights into the cross-talk between nitrite and ene-diols at the metal sites.