The behavior of continuous chem. reactors can be altered significantly by forced oscillation of reactor parameters, such as feed concn., flow rate, and temp. In contrast to autonomous oscillations in unstable systems, the forced periodic disturbances are controlled and can be used as a further parameter for process optimization. The dynamic behavior of individual steps of the overall reaction and of the reactor can be exploited to obtain performances and selectivities which cannot be accomplished in the traditional way on steady-state operation under comparable conditions. This is shown in discussing some simple kinetic schemes published in theor. studies and comparing them with exptl. results for homogeneous and heterogeneous reactions. The phys. and chem. causes for the predicted and obsd. advantages of periodic operation are discussed. [on SciFinder (R)]