In this paper, using L., a leaf-extracted, assisted microwave method (MM) was used to synthesize nickel oxide formation. We synthesized nickel oxide nanoparticles (NiO) with a crystal size in the range of 15-16 nm by a leaf-assisted microwave method (LAMM). The synthesized materials show that an X-ray diffraction (XRD) study confirmed the formation of a single phase structure exhibiting a crystallite size in the range of 15-16 nm using Scherrer's method. The nickel oxide prepared by the MM had a surface area of 60.35 m²/g, pore volume of 0.9427 cm³/g and an average pore diameter of 13.27 Å. Surface morphology was analyzed by the scanning electron microscope (SEM), X-ray photoelectron spectroscope, Brunauer-Emmett-Teller (BET) analysis, and the vibrating sample magnetometer (VSM). Catalytic activity (CA) tended toward the oxidation of styrene to benzaldehyde. The inexpensive catalyst tested is likely effective as a catalyst due to synergistic interactions between metal oxides with high dispersion. In comparison with other findings, LAMM is easy and eco-friendly. The current study obtained nanocrystalline NiO that was suitable for potential applications in catalysis. The synthesized NiO could potentially be used in therapeutic field due to their competent antibacterial activity.