The microscale revolution in chemistry promises to transform classical batch wise laboratory procedures into integrated systems capable of providing new understanding of fundamental chemical processes as well as rapid, continuous discovery and development of new products with less use of resources and waste generation. Applications of silicon based microreactors are illustrated with a broad range of cases studies, including high throughput experimentation in organic synthesis, integration of ultraviolet (UV), visible and infrared (IR) spectroscopy; investigations of high temperature heterogeneous catalytic reactions, obtaining high mass transfer rates in gas-liquid reactions over solid catalysts, enabling difficult to perform reactions, synthesis of solid nanoparticles, and high temperature conversion of hydrocarbons to hydrogen.