Results are presented for the variation of flame propagation velocity with rising explosion pressure for methane-air mixtures. The experiments were carried out in an explosion chamber with a volume of 1.25m3. Photos of the flame propagating during the explosion processes were obtained through a window in the middle of the front cover of the chamber. The influence of the methane concentration on the time delay between the flame front approaching the chamber wall and the moment when the pressure inside the chamber reached its maximum is also discussed.