The rate equations of localized transition model of thermoluminescence (TL) have been simulated by taking into account their stiff nature for wide range of recombination probabilities and frequency factors using linear and hyperbolic heating profiles without assuming the quasi-equilibrium (QE) approximation.The shape factors μ_g calculated for simulated glow curves vary from 0041-0.52 in linear heating profile and from 0.42-0.56 in hyperbolic heating profile. It is found that shape factors μ_g exhibit dependence on heating rates, thereby implying that QE approximation is not satisfied, hence supporting the doubt regarding validity of QE approximation expressed earlier by many workers. In conclusion, it is stated that under very strong re-trapping,it is possible to get non-first order kinetics in localized transition model.