To explore the dynamic mechanism of the hydroxyl radical generation from the ozone-water complex and its atmospheric implications, the intrinsic reaction coordinate computations and ab initio molecular dynamic simulations were used to map the minimum energy profiles of O-3 and O-3-H2O complex photo-dissociation and inspect photo-dissociation feasibility for different complex conformers. The stable trans isomer possesses a small portion in seven coexistent O-3-H2O complex conformers, 70% of which is the unique source to produce OH radicals in S-PP((D) over bar (1)A', (1)pi pi*) state. The quantum yield of atmospheric hydroxyl radical through the ozone-water complex photolysis is much lower than the previous expectation. (c) 2014 Elsevier B.V. All rights reserved.