Photodissociation dynamics of benzenesulfonic acid at 266 nm was studied by probing the nascent OH photoproduct using the single-photon laser-induced fluorescence technique. Measurements on the nascent OH fragment revealed that it was produced vibrationally cold and its rotational state distribution was Boltzmann-like, characterized by a rotational temperature of 840 +/- 70 K. The ratios of 2 Pi(3/2) to 2 Pi(1/2) states of the OH fragment were found to be more than unity and the population of the Pi(+) state for the Lambda-doublet was dominant. Based on both experimental and theoretical results, a probable mechanism for the formation of OH fragment produced from the photodissociation of BSA is proposed. (C) 2008 Elsevier B. V. All rights reserved.