The paper presents the results of two-dimensional simulations of the cellular structure of a detonation wave in a stoichiometric mixture of hydrogen with air. The dependence on cellular structure on chemical kinetics mechanism proved to be essential in terms of characteristic cell size. Comparison of simulation results with experimental data made it possible distinguishing the kinetic mechanism, which could describe the cellular structure for the conditions under investigations more adequately than other tested mechanisms. The dependence of cellular structure on mixture temperature and channel width was also investigated and comparative results are presented. It was shown in numerical experiments, that the dependence of cell size on temperature could be not monotonous due to manifestation of different effects under different mixture conditions. The cells can grow and then split giving birth to a fine structure.