The rate constant of bulk electron-ion recombination is calculated for dense gaseous krypton doped with CH4 and N-2. In the calculations, the electron scattering is modeled by experimental, energy-dependent collision cross sections. The applicability of the assumed cross sections is verified by calculations of the electron mobility in Kr/CH4 and Kr/N-2, which give a reasonable agreement with experiment. For both Kr/CH4 and Kr/N2, the recombination rate constant is found to increase with increasing concentration of the molecular species, due to efficient dissipation of electron energy in vibrationally and rotationally inelastic collisions. The simulation results are compared with experimental data, which also demonstrate an enhancement of the recombination rate by molecular additives.