The flame stabilization mechanism of a methane-air edge flame formulated in a narrow channel was experimentally investigated and compared with a simple analytical model. Non-premixed flames were classified into premixed flame modes and edge flame modes. The correlation between the propagation velocity and the fuel concentration gradient in a narrow channel was investigated and the applicability of ordinary edge-flame theory was appraised. (C) 2009 The Combustion Institute. Published by Elsevier Inc. All rights reserved.