The influence of the MoO42- ions on the Bray-Liebhafsky (BL) oscillatory re
action is described. The MoO42- ions affect the values of the parameters of
the BL reaction; first of all, they decrease the induction period and the
duration of oscillations, but they increase the average frequency of oscill
ations. A qualitative explanation of this influence is based on the Treindl
-Noyes skeleton mechanism of the BL oscillatory reaction. The production of
singlet oxygen (O-1(2)) by the disproportionation of hydrogen peroxide cat
alyzed by molybdate ions, which is obviously quenched physically and/or che
mically, may play a role too.