Monte Carlo simulation is used to study the influence of the time evolution of the target temperature on the characteristics of the laser-ablated flow. The time dependencies of the flow parameters at the border of the Knudsen layer are compared with these at the target. Moreover, the mean number of collisions and the backscattered flow are obtained for different desorption fluxes. The effect of the time evolution of the desorption flux on time-of-flight ~TOF! distributions is considered, and a possible explanation of the inconsistencies that frequently appear when TOF is fitted by Maxwell– Boltzmann distribution is proposed.