A one-dimensional analytical model of a direct methanol fuel cell (DMFC) was presented. This model was developed to describe the electrochemical reactions on the anode and cathode electrodes, and the transport phenomena in fuel cell consisting of methanol transport from anode to cathode through the membrane (methanol crossover), diffusion of reactants in gas diffusion layers (GDLs), and fluid flow in flow channels. One of the main strike features of this work was that the complicated relations were simplified logically and the model was solved analytically by the first-order differential equation. The results of the model indicated that increasing the current density led to lower methanol concentration in anode in spite of higher oxygen concentration in cathode. The presented model supports the experimental data well.