A microkinetic model which successfully explains the steady-state kinetics of ethylene oxidation on silver is used to simulate transient surface science experiments. The model explains a number of important TPR experiments in the literature. It is demonstrated that a model with a common intermediate for epoxidation and combustion may explain these experiments, lending further support for the crucial role of oxametallacycles in ethylene epoxidation. It is suggested that the role of subsurface oxygen is to serve as an oxygen reservoir in transient experiments without oxygen atmospheres, but are otherwise unimportant. (C) 2004 Published by Elsevier Inc.