AbstractUnder constant external conditions, chemical reactions may also proceed in a rhythmic manner. The kinetic mechanisms responsible for such oscillations prove to be unexpectedly complicated. It can nevertheless be demonstrated that chemical periodicity is caused by certain kinds of coupling between simultaneous reactions or transport processes. A general survey of the chemistry and phenomenology of the principal chemical oscillations is followed by a discussion of the situations leading to periodic reactions on the basis of the multivariable kinetics of feedback systems. Autocatalysis and autoinhibition play an important role, as also do kinetic instability and spatial propagation.