AbstractVarious physical systems with either phase boundaries or semi‐permeable membranes can give rise to a confined chemical reaction. An analysis was performed to show the strong and potentially important effect of this confined reaction on chemical species diffusion through the region of reaction. The reaction was treated as one near equilibrium in order to obtain an analytical solution and to illustrate the strong coupling of fluxes caused by the reaction. Some generalities, e. g., facilitated diffusion of a single species transferring, were deduced using the above conditions and assumptions. These generalities are necessarily valid only for a single near equilibrium reaction with constant diffusivity of non‐diffusing species. Three examples were solved to illustrate the strong coupling of mass flu