The residence time distribution for the flow of liquid reactants containing electrolytes in a cylindrical microreactor is derived under the conditions of constant surface potential and negligible end effects. The influences of the key parameters, including the thickness of the double layer, the strength of the applied electric field, and the magnitude of the applied pressure gradient, on the behavior of residence time distribution are discussed. The results obtained provide necessary information for the design and optimization of microreactors which involve liquid electrolyte reactants. The results of the numerical simulation reveal that a thin double layer, a strong applied electric field, and a greater applied pressure gradient lead to a faster fluid flow and, therefore, a short residence time. We show that if κ a ≤ 0.001 the residence time distribution can be approximated by that for the case of a laminar flow, and if κ a ≥ 500, the residence time distribution can be approximated by that for the case of a plug flow, with κ and a being the reciprocal Debye length and the radius of the microreactor, respectively.