The phenoxyl radical formation mechanism from the UV-photolysis of ligno-p-cresol in organic solvents has been investigated by steady-state and time-resolved EPR spectroscopy. It is suggested that the phenoxyl radical is generated from the o-methoxy phenol moiety in the main chain of the polymer through the dissociative photoionization by the biphotonic process from the excited triplet states. (C) 2003 Elsevier B.V. All rights reserved.