Nano materials find wide applications due to their behavior at nano scale. TiO2 nanoparticles (TiO2 NPs) was synthesized using Neem leaf extract. This is simple, rapid, eco-friendly, cheaper and green tools for TiO2 NPs synthesis using agricultural waste at lower applied temperature. Characterization of the extracted TiO2 NPs was confirmed by XRD, SEM, EDAX, TEM, HR-TEM, SAED, and FT-IR, respectively. The catalytic activity of TiO2 NPs was investigated in synthesis of 1,2- dihydroquinoline derivatives with excellent yields and low cost. Purification of the synthesized 1,2-dihydroquinoline derivatives carried out by easy work-up of nonchromatographic methods