The effect of Poiseuille flow on the convective stability of electrochemical system is considered. It is found that the effect is destabilizing in the case of oscillatory instability in the system. It is shown that this effect is caused by the fact that the problem is not self-conjugate, because the system is multicomponent. In addition, it is found that the effect of Reynolds number on the stability of these systems is linear at small Reynolds number. in contrast to the self-conjugate Rayleigh-Benard problem, where the effect is quadratic. (C) 2008 Elsevier Ltd. All rights reserved.