Dynamics of laminar triple flame investigated numerically for the different mixture degrees. One-step methane-air chemistry adequate to reach and lean mixture combustion was accepted. Velocity of triple flame is determined as a function of methane concentration logarithm gradients mu = d(In Y-1)/dx (characterizing mixing degree). It is found that maximum velocity of the triple flames correspond to the value of the methane concentration logarithm gradients mu approximate to 1000 m(-1) for plain and mu approximate to 2000 m(-1) for axis-symmetrical channels. The maximum velocity of triple flame in plain and axis-symmetrical channels in the case of non-gradient incoming gas flow is about twice bigger than normal laminar flame velocity S-f approximate to 2.1S(1). (C) 2007 Elsevier Ltd. All rights reserved.