A theoretical approach to the current vs. time behavior of arrays of hemispherical or disc-shaped microelectrodes is presented. The treatment includes the chronoamperometric response to changes of the applied potential, and the dynamic response to changes of the concentration or the flow velocity of the sample solution. The theory accounts for effects of the Nernstian diffusion layer arising between sample bulk and electrode surface. The influence of different geometric parameters on the response characteristics is discussed. Arrays with a low packing density of electrodes are shown to yield the multiple response of a single microelectrode, whereas closely packed arrays mimic the behavior of a conventional macroelectrode of the same total surface area.