Application as well as detection of different chemicals plays an important role in the progress of modern science and technology. The beauty of various characteristics of materials and the inherent logic behind their working mechanisms can be wisely utilized for sensing different chemicals. The mechanisms as well as performances of different materials viz. carbon nanotube, graphene, metal oxides, biomaterials, luminescent metal-organic frameworks, hydrogels, textiles, quantum dots, ligands, crown ethers etc. for identification of different chemicals has been discussed here. This book would be a valuable reference to select suitable materials for possible use in chemical sensors.