An edge flame was established in a counterflow field with a stretch rate gradient using twin rectangular burners which were misaligned by a few degrees. The stretch rate gradient was quantitatively defined as a function of the angle between the two burners and the distance from the edge of the burner, and thus the effect of stretch rate gradient on the behavior of the edge flame was investigated. The local chemical reaction rate at the edge of a CH4/air flame was stronger than that at other parts of the flame. On the other hand, the reaction rate at the edge of a C3H8/air flame was weaker than that of other parts of the flame. The curvature of the flame edge of the CH4/air flame was much larger than that of the C3H8/air flamed These results are thought to be due to the effect of the Lewis number. The ratios of the local stretch rate at the. flame edge to the extinction stretch rate for planar twin flames with the same composition as the edge flame were 0.5 to 0.7 for the CH4/air flame and 0.6 to 0.8 for the C3H8/air flame. These values were midway between those in the numerical simulation by Daou and Linan and those in the experiment by Liu and Ronney. Moreover, it was-shown that an increase in the stretch rate gradient resulted in a lower local stretch rate at the flame-edge. Behavior of the edge flames did not depend on the Lewis number of the mixture. (C) 2003 The Combustion Institute, All rights reserved.