Carbon dioxide is one of the main contributors to the global warming. The efforts to minimize generation and sequestration of CO2 are of great importance. Electrolytes have great role on the CO2 reduction. We have found that the use of solid polymer electrolyte (SPE) further enhances the process and also helpful to form the products selectively using direct electrochemical reduction of carbon dioxide (dERC). However, SPE is not explored in great extent for dERC. Hence, the main objective of this book is to understand the significance of SPE and suitably develop it for dERC. This book systematically covers the design of an electrochemical reactor, synthesis and characterization of solid polymer electrolytes and its evaluation in the electrochemical reactor. The book provides the insight on the role of SPE structure and functional groups in SPE as well as new mechanisms to understand the direct electrochemical conversion of carbon dioxide to value added products. This book will be helpful to the researchers and academicians for the development of solid polymer electrolytes especially for the efficient dERC.