Silver nanowires and nanoparticles are synthesized by a polyol method in a millifluidic reactor. We have been able to optimize the flow chemistry reaction conditions to get a high yield of nanowires in a continuous flow. By changing reaction parameters we have demonstrated the synthesis of single crystalline silver nanoparticles in a rapid reaction time of only 3 minutes. All results are compared with standard batch and microwave reactions. An example of application is provided through the silver nanowire assisted etching of silicon wafers. This colloidal approach of metal assisted silicon etching allows transferring of the nanowire shape to silicon.