The book includes studies on the Photoinduced Processes in Conventional Solvents, Room Temperature Ionic Liquids (RTILs) and Proteins. The book consists of seven chapters. Chapter 1 is the introduction part of the whole book. Chapter 2 includes the detail description of materials, methods and instrumentation for carrying out the work. Chapter 3 to 6 are working chapters, where chapter 3 and chapter 6 provides a detailed study of the nonradiative processes in some structurally flexible Electron Donor Acceptor systems in conventional solvents and protein media. Chapter 4 describes Photoinduced Electron Transfer with molecular systems having fluorophore-spacer-receptor architecture. The effect of the Room Temperature Ionic Liquids (RTILs) on the mechanism and kinetics of Excited state intramolecular proton transfer (ESIPT)reaction constitutes the 5th chapter. Chapter 7 summarizes the whole work in the book and also outlines the scope of future work.