Continuous periodic forcing of many non-linear processes can prove superior to the conventional time-invariant operation. The application of Pontryagin's maximum principle to periodic optimization is considered. An efficient general algorithm for the synthesis of optimal lumped-parameter periodic processes is developed. The successive linearization procedure used does not require a priori assumptions about the input waveforms and yields a necessary condition for the existence of optimal periodic processes. The convergence characteristics of the algorithm are illustrated by the computational results obtained for a chemical reactor problem.