The 266 nm photodissociation of gaseous nitrobenzene has been studied by monitoring the NO X (2)Pi product using the single-photon laser-induced fluorescence technique. The rotational population and internal energy distributions of fragment NO product were determined. In the experiment, we only observed the rotational state distributions of the NO fragment for v(')=0. The rotational state distributions of the nascent NO photofragment can be characterized by a Boltzmann temperature of 3300+/-300 K. Ab initio calculations were performed to characterize the transition state and to determine the barrier height for the rearrangement of nitrobenzene to phenylnitrite. A clear photodissociation picture has been proposed theoretically. (C) 2003 American Institute of Physics.