Chemiluminescence occurs when the exothermicity (ΔG) of a chemical reaction is converted into electronic excitation energy(*) of a reaction product

which then emits photons of light (

hv

). We can describe chemiluminescence as a

ΔG

→:→

hv

sequence. The heart of the sequence is the chemi-excitation (

ΔG

→)step.The field of chemiluminescence has experienced tremendous growth and witnessed significant advances in the past more ten years. To a large extent

the recent progress toward the understanding of chemiluminescent processes can be attributed to achievements in three general areas. The first area of achievement was the discovery and subsequent intensive investigation of the chemiluminescent reaction of 1

2-dioxetanes. The discovery of this reaction

a simple unimolecular rearrangement

has allowed experimentalists to focus on the study of the key step of chemiexcitation. A second area of recent advance has come in the field of electron-transfer chemiluminescence. Electron-transfer chemiluminescence has been investigated extensively as elctro-generated chemiluminescence (ECL). Using ECL technique significant progreas has been made in recent years toward the understanding of chemiexcitation by electron transfer. A third general area of recent progress has been the confirmation of chemically initated electron-exchange luminescence(CIEEL) as a general mechanism for the general chemical formation of light.In this review we have introduced the classification of chemiluminescent organic reactions

examined the general requirements for a reaction to be chemiluminescent

presented the three important generalized mechanisms of chemiluminescence in solution

and finally enumerated some important chemiluminescent systems.