Chemical microreactors for chemical systhesis and their methods of manufacture are known, but have disadvantages such as extremely high manufacturing costs or poor flexibility for adaptation to various cases of application. These disadvantages are avoided by means of the microreactors and manufacturing methods according to the invention. The microreactors are characterized in that the reactors contain fluid ducts in at least one plane as well as feed and return lines for fluids, wherein the fluid ducts are defined by side walls of metal opposing each other and further side walls of metal or plastic extending between said side walls, and in which the planes are connected together and/or with a closure segment closing open fluid ducts by means of appropriate solder or adhesive layers. The manufacturing method is characterized by process sequences in which the individual reactor planes produced by means of electrolytic methods, are connected together by soldering or gluing.
