Pyridazine belong to an important group of heterocyclic compounds and lot of research work on has been done in the past. The substituted pyridazinone derivatives have attracted considerable attention due to their characteristic pharmacological activities. Various substitueted pyridazine derivatives have been used as clinically used drug molecules. These diverse pharmacological activities promoted us for the synthesis of various substituted pyridazinone derivatives in order to explore the usefulness. In the present review, various synthetic chemical methods have been studied for the synthesis of different types of substituted pyridazinone derivatives. The behaviour of the pyridazinone toward formaldehyde/piperidine, ethyl chloroacetate, chloroacetic acid, benzenesulfonyl chloride, bromine/acetic acid and aromatic aldehydes has also been studied. However, the chloro-derivatives are resulting from the reaction of pyridazinone with phosphorus oxychloride. The behavior of chloropyridazine toward hydrazines, thiourea, sodium azide, anthranilic acid, aromatic amines and sulfa compounds has also been considered. The thio pyridazinone derivatives were prepared from the reaction of pyridazinone with phosphorus pentasulfide.