Over their designed lifetime, high-temperature electrochemical devices, such as solid oxide fuel cells (SOFCs), can experience degradation in their electrochemical performance due to environmental conditions, operating conditions, contaminants, and other factors. Understanding the different degradation mechanisms in SOFCs and other electrochemical devices is essential to reducing performance degradation and increasing the lifetimes of these devices. In this paper, SOFC degradation mechanisms are evaluated, and a damage model is presented that describes performance degradation in SOFCs due to damage or degradation in the SOFC electrodes. A degradation classification scheme is presented, dividing the various SOFC electrode degradation mechanisms into categories based on their physical effects on the SOFC. The damage model and classification method are applied both to sulfur poisoning and antimony poisoning, which occur in the SOFC anode. For sulfur poisoning, the model can calculate degradation in SOFC performance based on the operating temperature of the fuel cell and the concentration of gaseous sulfur species in the anode. For antimony poisoning, the effects of nickel consumption from the anode matrix are investigated.