A prototype direct methanol fuel cell (DMFC) stack has been designed and built at Newcastle University, based on a flow bed design developed with the aid of a flow visualization study and fluid flow modelling. In addition, a series of engineering models have been developed that predict the stack voltage, fluid distribution from the stack manifolds, the overall system pressure, the chemical equilibrium in both anode and cathode flow beds and the thermal management of the stack. The results of this work are presented in terms of an overall engineering model that incorporates all the aforementioned models. The initial steady state performance data of the prototype stack presented was obtained as a result of our experience of scaling up the system to achieve the designed power outputs.