The generation and propagation of chemical waves in the Belousov-Zhabotinsky (BZ) reaction were investigated using a cation-exchange membrane embedded with a metal catalyst as a 2-dimensional oscillatory/active field. We found that a target pattern is generated from the top of a V-shape, indicating that the apex on the boundary between active and passive fields behaves as a pacemaker. A Plausible mechanism for this phenomenon is proposed based on a reaction-diffusion equation. (C) 2010 Published by Elsevier B.V.