The limiting current of nitrite reduction in acid media is usually controlled by a preceding chemical reaction occurring in a very thin reaction zone. We propose that the apparent current density of this kind of reaction can be effectively enhanced by using a porous electrode and, for analytical purposes, the powder microelectrode (PME) is a convenient version. The apparent limiting current densities of nitrite reduction at the PMEs made from Au and carbon powders are found to be 50 and 100 times larger, respectively, than those obtained with smooth electrodes. For the carbon PME, the current is linear with nitrite concentration spanning five orders of magnitude with a lower detection limit of 4.4 mu mol l(-1).