This chapter contains sections titled: Introduction to Direct Methanol Fuel Cells Main Types and Structures of Direct Methanol Fuel Cells Electrochemical Processes in Direct Methanol Fuel Cells Fuel Cell Components Assembly and Manufacturing of Direct Methanol Fuel Cells Direct Methanol Fuel Cell Stacking and Systems Direct Methanol Fuel Cells: Performance, Testing, and Diagnosis Degradation Mechanisms and Mitigation Strategies Applications Challenges and Perspectives of Direct Methanol Fuel Cells References