Utilizing pulse radiolysis and kinetic spectrophotometric monitoring techniques, rapid electron transfer reaction from thymine and thymidine anion radicals to caffeic acid was observed respectively. Anion radicls of caffeic acid with absorption maximum at 360 nm have been generated via foregoing electron transfer reaction with rate constant of 1×10,9,mol,-1,L s,-1,. Accordingly the subsequent protonation of thymine anion radicals should be prevented by the electrophilic protector. These kinetic demonstrations have provided direct evidence of charge transfer protection mechanism.