This chapter contains sections titled: Part A: Direct Methanol Fuel Cells Methanol as a Fuel for Fuel Cells Current-Producing Reactions and Thermodynamic Parameters Anodic Oxidation of Methanol Milestones in DMFC Development Membrane Penetration by Methanol (Methanol Crossover) Varieties of DMFCs Special Operating Features of DMFCs Practical Models of DMFCs and Their Features Problems to Be Solved in Future DMFCs Part B: Direct Liquid Fuel Cells The Problem of Replacing Methanol Fuel Cells Using Organic Liquids as Fuels Fuel Cells Using Inorganic Liquids as Fuels References