The application of silicon microfabrication technologies to electrochemical devices allows reduction of overall device package to potentially increase volumetric power densities. This review first focuses on some exciting developments in microfuel cells, in particular, solid oxide fuel cells (SOFCs) and proton exchange membrane fuel cells (PEMFCs). The emphasis is given to innovative 2D processing methods, novel 2D architectures of microfuel cells, and demonstrated performance in terms of area power densities. Emerging 3D fabrication techniques that are potentially promising to produce 3D electrochemical devices such as 3D cell and stack architectures on the micrometer scale will then be discussed. Lastly this paper highlights some new opportunities in electrode kinetics studies enabled by microfabricated devices-investigation of scaling relationship between microelectrodes and electrochemical responses, which has led to improved fundamental understanding of electrode reactions and rate-limiting steps. Copyright (C) 2007 John Wiley & Sons, Ltd.