C-Si Bond dissociation in highly excited triplet (T-n) states of p-phenylbenzylphenylsilanes (PBPS) was found using stepwise two-color laser photolysis techniques. PBPS undergo the C-Si bond cleavage in excited singlet states with quantum yields of 0.02-0.03, whereas they did not decompose in the lowest triplet (T-1) states. Upon the second laser excitation of the T-1 states, the C-Si bonds were found to cleave with quantum yields of 0.04-0.06. From the viewpoint of the bond dissociation energies of the C-Si bonds, the dissociation profile in the T-n state of PBPS was discussed. (c) 2007 Elsevier B.V. All rights reserved.