KBrO3 and H2SO4 produce an oscillating system in batch when the proper combination of substrate concentrations, stirring rates, and temperatures is used. Bromide present as an impurity in KBrO3 also takes part in the reaction. In many Belousov-Zhabotinsky (BZ) systems the above substrates are used and mixed with only an organic substance or with an organic substance and a catalyst, and the simple bromate oscillator cooperates with an organic substance, a catalyst, or both. The bromate oscillator found in this work is the simplest one in the BZ system composed of BrO3-, H2SO4, an organic substance, and a catalyst.