Total quenching (k(r) + k(q)) and chemical reaction rates (k(r)) for the removal of singlet oxygen by 2,3’,5’-tris((tert-butyldimethylsilyl)oxy)guanos (1) and its oxidation product, 2’,3’,5’-tris((tert-butyldimethylsilyl)oxy)-7,8-dihydro-8-oxoguanosine (2), were determined by the time-resolved infrared luminescence technique and competition experiments, respectively. Compound 2 is two orders of magnitude more reactive with singlet oxygen than 1. A mechanism for the formation of 2 from 1 with singlet oxygen is proposed.