The catalytically coated ceramic plate heat exchanger represents a specialized microreactor offering a large surface‐to‐volume ratio and improved temperature control. Appropriate and economically viable manufacturing processes are presented together with the results of coating studies and thermal and reaction engineering investigations. The selective methanation of carbon monoxide, used as purification step for H2‐rich gas streams in stationary fuel cell applications, was chosen as a suitable test reaction because of its strongly exothermic behavior and its need for tight temperature control.