In Chapter One, L. Khotseng and G. Vaivars provide an overview of the recent advances in electrocatalysts for direct methanol fuel cells for both anode and cathode catalysts in order to present direct methanol fuel cells as an alternative power source for portable devices. In Chapter Two, Nobuyoshi Nakagawa, Mohammad Ali Abdelkareem, Takuya Tsujiguchi, and Mohd Shahbudin Masdar propose a fuel supply layer using a porous carbon plate (PCP) for DMFCs allowing for the use of high methanol concentrations. The proposed layer is comprised of a thin PCP layer, as well as a gap layer that has a mechanism to supply the methanol as a vapor. Next, Chapter Three by D.S. Falcao, J. P. Pereira, and A.M.F.R. Pinto review the multiphase flow in fuel cells modeling approaches while also reviewing the flow visualization techniques for flow analysis in fuel cells. Chapter Four by B.A. Braz, V.B. Oliveira, and A.M.F.R. Pinto closes the book by discussing the key work that has been done to improve the passive DMFC performance and providing a review on the most recent developments in passive DMFCs.