Fuel cell systems are being commercialized today. Most noteworthy are low-temperature PEM fuel cell systems that are economically attractive for applications including backup power systems and material handling (forklifts). Usually these systems are fueled using cylinders of compressed hydrogen, an expensive and inconvenient source of fuel. This book details the state-of-the-art of fuel cell systems incorporating methanol reformers as the source of purified hydrogen (rather than compressed hydrogen). Beginning with an overview of PEM fuel cells, the book discusses the various technical approaches to methanol reforming and hydrogen purification. A unique theme that is carried throughout the discussion is the practical aspects of commercial applications that favor one technical approach over another, any why. The reader will gain an understanding of the chemistry, engineering, economics, and agency certification requirements that ultimately shape the optimal approach for methanol fuel cell systems targeting commercial applications.