The photophysical and photochemical properties of exciplexes are summarized considering the electronic structure and role of energetics and kinetics in the formation and stabilization of these molecular entities. Exciplexes involving transition metal complexes, are known as transition metal complex exciplexes (TMCEs) and are classified on the basis of the reactive site of the excited metal complex and the properties of the ground state reactant. There are two main groups; ligand-centered exciplexes and metal-centered exciplexes. A survey of the literature of TMCEs is presented. Common features of exciplexes classified into different groups are revealed. A strategy for searching for new TMCEs is suggested.