Pulse radiolysis of aqueous 4-chlorophenol in dilute solutions under different conditions was studied. The main characteristic peaks in these transient absorption spectra were attributed and the bulid-up/ decay trends of several transient species were investigated. Under alkaline conditions, the reaction of Oh radical and 4-chlorophenol produces chlorinated phenoxyl radical with a rate constant of 4.14× 10^9L/mol·s);while under acid conditions, the initial product is mainly OH-adduct. The reaction of H with 4-chlorophenol produces H- adduct with a rate constant about 2.0×10^9L/(mol·s) and the intemediate can remove Cl from itself gradualy through a second-order reaction. In alkaline solutions, eaq^- can capture Cl directly from 4- chlorophenol with a rate constant about 1.82×10^9L/(mol·s).

Key words: PULSED IRRADIATION, RADIOLYSIS, TRANSIENT PERFORMANCE, ABSORPTION SPECTROMETRY, DILUTE SOLUTION, FREE RADICALS