Mathematical modeling of electrochemical systems on the continuum scale will be reviewed in this presentation by way of several examples taken from my career. The purpose of such modeling is usually to develop a model that can be used to make predictions of the performance and perhaps the degradation of an electrochemical system of interest. Typically, we seek a model that is as simple as possible, but does not “throw the baby out with the bath water.” In addition, we seek a model that does not require significant computation time since it is necessary to validate the model based on experimental data. It has been and still is a challenge to develop a model of an electrochemical system of interest in a timely manner so that it will be useful in industry. Fortunately, software such as COMSOL Multiphysics is available now to assist in the development of models of electrochemical systems and includes a significant library of such models. Several examples of industrially useful mathematical models of electrochemical systems will be presented.