Abstract Nonlinear phenomena arising from the interaction of two oscillating systems of chemical reactions are studied experimentally. The system of two connected flow-through continuous stirred tank reactors (cells) with controlled exchange of reaction mixture is used. The Belousov reaction (oxidation of malonic acid by bromate in sulphuric acid with ceric/cerous ions as catalyst) served as model system. The frequency of oscillations was controlled by change of the reaction temperature. Phenomena such as synchronization of oscillations at a common frequency, synchronization at multiples of a common frequency, rhythm splitting and amplitude amplification were observed, depending on the degree of interaction and the differences in the original oscillation frequencies. Mathematical modelling of the above phenomena failed, probably due to insufficient knowledge of a kinetic model.