The products of ozone dissociation occurring on glass surface are enriched in heavy oxygen isotopes (O-17 and O-18) in a mass independent (Deltadelta(17)O/Deltadelta(18)O = 1.0) fashion. Such behavior is in contrast to the case of thermal dissociation where fractionation is mass dependent (Deltadelta(17)O/Deltadelta(18)O = 0.5). Even photo-dissociation by visible light is a mass dependent process. The mass independent fractionation in surface dissociation can probably be explained by assuming that the dissociation takes place via a short-lived complex involving the ozone molecule and an active surface site. The anomalous isotopic fractionation in surface dissociation can be useful to decipher the mechanism of surface reaction in some cases. (C) 2003 Elsevier Science B.V. All rights reserved.