This study describes a numerical effort to predict pollutant species such as CO and NO formed in premixed turbulent flame using an extended coherent flame model. This model is used to predict pollutant emissions of methane-air combustion. A semi-global kinetic scheme is tested, using a two steps reaction mechanism of Westbrook and al. The model combines coherent flame model to estimate the CO formation and the well-stirred reactor concept for calculating the NO and all other species which are taken into account in this investigation. Essentially, we assume that CO is analysed near the flame zone because is formed with very fast intermediate reaction compared to the other characteristic times. Other species formed with longer time are supposed to take place in high temperature region where can be consider that corresponding kinetics are best represented by homogeneous reactor conditions. Numerical results for emission species and dynamic parameters in premixed flame of methane-air are given for a duct combustor where the flame is stabilised behind a rod flame holder with a blockage ratio is taken as 6% and a mass flow rate m(a) = 35 g/s.