Book excerpt: This book gives comprehensive information on the design, preparation and application of organic-inorganic composite membranes that are used for molecular separation. Various membrane types with different materials are highlighted, including polymer/ceramic composite membranes, mixed matrix membranes, metal-organic frameworks membranes and graphene-based membranes. Physical and chemical properties, morphologies, interfacial behaviors, transport characteristics and separation performance of the organic-inorganic composite membranes are thoroughly discussed based on advanced characterization techniques.Meanwhile, the book contains several typical applications of the membranes in fields such as bio-fuels production, organic compounds recovery, solvent dehydration, carbon dioxide capture and others. In addition, large-scale production and industrial implementation of the organic-inorganic composite membranes are briefly introduced.