The laminar flame speeds of CH4/O-2/CO2 mixtures in atmospheric conditions (300 K and 1 atm) were studied using a Bunsen burner. The surface area methodology based on images of flame was performed to obtain the laminar flame speeds for a range of equivalence ratios (from 0.6 to 1.4, step 0.1), oxygen concentrations (from 25% to 35%). The experimental data were compared to numerical flame speed predictions which was based on GRI-Mech.ver 3.0 mechanism using a Chemkin package. The results showed that the maximum of flame speeds appeared at the stoichiometric ratio. With an increase in O-2 concentration, the flame speeds increased. The effect of CO2 dilution was also investigated with experimental measurements, flame structure analysis and reaction pathway analysis from calculation. In premixed CH4/O-2/CO2 flame, the combustion reactants, important intermediate and products concentration became lower and the flame thickness became thicker compared to CH2/O-2/N-2 mixtures. The major oxidation pathway of CH4/O-2/CO2 remain unchanged but contribution rates of major intermediates formation have changed a lot. In addition, a part of secondary chemical pathways have changed. (C) 2014 Elsevier Ltd. All rights reserved.