An analytical method using the concept of diffusion in energy space is applied to calculate the electron-ion recombination rate constant and the electron escape probability in dense gaseous argon and krypton. The results are compared with the respective data obtained from computer simulations. The discrepancies between the two methods are found to be relatively small. The applicability of the energy diffusion approach is discussed. (C) 2000 American Institute of Physics. [S0021-9606(00)01708-6].