The small scale structure of premixed methane/air flames, stabilized on perforated or porous flat-flame burners has been studied numerically. The two-dimensional combustion equations have been solved, using the vorticity-stream function formulation for the flow field and two different chemistry models: the skeletal mechanism for lean methane combustion and a one-step scheme. The curvature of the flames, predicted by both models is comparable. The range of pore sizes, porosities and mixture velocities, which can be used to create practically undistored flat flames has been determined. It is found that more-dimensional transport effects are negligible in flames, stabilized on the flat-flame burners recently introduced by (Maaren van, 1994) for measuring burning velocities with the Heatflux method. This guarantees that the measurement data are not obscured by small scale distortions and can be compared with 1D modeling results.