The ratio of the probabilities of population of the isomeric and ground states, so called the isomeric ratio is closely connected
to the angular momentum of the initial fission fragments that is dissipated at the later stages of gamma ray cascade. This
ratio also provides important information on the nuclear level structure as well as the nuclear reaction mechanism involved.
In this work, the isomeric ratio in fission fragment 135Xe from photofission of 233U induced by 23.5 MeV bremsstrahlung has been determined by the method that uses inert gaseous flow. The results have been
discussed and compared with that of other authors.