This account presents an overview of our recent endeavors to achieve practical organic syntheses using a variety of microreaction devices. Herein are our achievements in ionic liquid-based catalytic reactions, photochemical transformation, and heterogenous hydrogenation reactions, where flow regime precisely controls residence time and product selectivity. 1 Introduction 2 Cross-Coupling Reactions Using Ionic Liquids and Microflow Systems 2.1 The Sonogashira Coupling Reaction in a Microreaction System 2.2 The Mizoroki-Heck Reaction in an Automated Microflow Production System 2.3 Carbonylation in an Ionic Liquid and Application to a Microflow System 3 Photo- and Radical Reactions in a Microflow System 4 Gas-Liquid-Solid Triphasic Catalytic Reactions in a Microflow System 5 Conclusion