Benzaldehyde phenylhydrazone is used primarily in organic synthesis as an intermediate for the preparation of heterocyclic compounds, particularly in the synthesis of indoles and other nitrogen-containing rings through cyclization reactions such as the Fischer indole synthesis. The formation of this compound from benzaldehyde and phenylhydrazine is utilized in analytical chemistry as a derivatization method for the identification and quantification of aldehydes, especially benzaldehyde. It also finds application in the development of pharmaceuticals and agrochemicals due to its participation in condensation and rearrangement reactions. Its stability and reactivity make it valuable in research laboratories for constructing complex molecular frameworks.