Nanoparticles are used, or being evaluated for use, in many fields, such as medicine, manufacturing, materials, energy, electronics, and environment. The characteristics of nanocrystals are strongly influenced by their physical dimensions and shape, which are tune by adjusting a plethora of experimental conditions, such as reagents concentration, reaction temperature and time. This demands for a large number of experiments to be carried out, mainly using a trial and error methodology. This publication describes a conceptual design of an unmanned microfluidic reactor for the optimization and production of nanoparticles with predefined physicochemical properties, with special emphasis on the production of gold group metal particles.