; Sustained oscillations in the concentration of free fluoride ions can be generated when the BrO3--SO32--Mn(II) oscillator is coupled either to Al3+-F- complex formation or to the Ca2+-F- precipitation process in a flow reactor. By careful analysis of the relevant equilibria and optimization of the reactant concentrations, one can obtain [F-] oscillations of several orders of magnitude as measured with an ion-selective electrode. The BrO3--SO32--Mn(II)-Al(NO3)(3)-NaF system also exhibits bistability, that is, simultaneously stable steady states of high and low [F-].