In this study, KF impregnated natural natrolite zeolite nanoparticle was reported as a new and economical heterogeneous catalyst. Different spectroscopic and microscopic techniques were utilized for confirming the structure of nanocatalyst such as FT-IR, XRD, FESEM, EDX, DLS, zeta potential and BET analyses. The KF/Natrolite NPs as a high performance catalyst was employed for the preparation of a new family of substituted benzo[e][1,4]-diazepin-5-ones using the one-pot condensation reactions of isatoic anhydride, primary amines and α-haloketones at 50 °C under solvent free condition. The some advantages of this procedure are the short time of reaction, high yields of product, easy separation of catalyst and products. Due to having benzazepine core, we investigate antioxidant property of some synthesized compounds by diphenyl-picrylhydrazine (DPPH) radical trapping experiment. It was observed that the compounds 4a and 4b had good DPPH• radical scavenging.