Chemical warfare agents (CWAs) are a growing concern to many countries. The use of CWAs by terrorist, organizations or even states is significant as they can be readily synthesized by simple chemical reactions and often has an extremely high toxicity. Unfortunately, there is incidence of CWAs being used in human history and some countries including the USA. These chemicals were used on a large scale during the 1st World War and caused approximately 1.3 million casualties.1 Sulfur mustards were used in 1980-1988 in the Iraq-Iran conflict being responsible for about 4% of all casualties. Nerve agents were used against the Kurds in Iraq and also in the terrorist attack on the Tokyo subway in 1995. Research into new CWAs, their production and use still continue in different areas around the world. Given the potential threat from these lethal agents, it is imperative to have an early warning system consisting of readily deployable sensors. In this book the author explored all the currently available technologies and showed the possibility and limitations of the currently available technologies and then proposed a more sophisticated, highly responsive ultra sensitive sensor for CWAs.