C-O bond dissociation of naphthoxymethyl compounds NpO-CH2R (Np = alpha- or beta-naphthalene moiety, R = Ph or Me) in the higher triplet excited state (T-n, n >= 2) was investigated using two-color two-laser flash photolysis. The C-O bond dissociation was found to occur with quantum yields (phi) of 0.06 and 0.07 for alpha- and beta-NpO-CH2Ph(T-n), respectively. With the use of reported data on C-O bond cleavage in NpCH2-OPh(T-n) and NpCH2-OMe(T-n), it was concluded that phi is related to the T-n-state lifetime and the energy barrier between the Tn state and dissociative potential surfaces. (C) 2007 Elsevier B.V. All rights reserved.