<![CDATA[General Background Nanotechnology continues to drive innovations across environmental remediation, energy storage, and biomedical engineering through sustainable nanomaterial design. Specific Background Among metallic oxides, nickel oxide nanoparticles synthesized via eco-friendly plant extracts present significant advantages over conventional chemical routes due to lower toxicity and cost-effectiveness. Knowledge Gap However, the precise structural and morphological characteristics of nickel oxide nanoparticles synthesized using Roselle leaf extract remain insufficiently characterized. Aims This study investigates the green biosynthesis of nickel oxide nanoparticles utilizing Roselle leaf extract as an eco-friendly reducing agent. Results X-ray diffraction analysis confirms the high-purity crystalline structure of the synthesized nickel oxide, while field emission scanning electron microscopy reveals spherical, highly agglomerated clusters alongside single-dispersion rod-like morphologies. Novelty This work establishes a sustainable, single-step green synthesis path utilizing Roselle leaf phytochemicals without toxic external capping agents. Implications These findings demonstrate a viable eco-friendly strategy for producing highly crystalline nickel oxide nanostructures for advanced technological applications. Key Findings Highlights Highly crystalline nickel oxide nanoparticles were successfully biosynthesized using roselle leaf phytochemicals. Structural characterization confirmed a high-purity crystalline phase with distinct diffraction profiles. Morphological analysis demonstrated spherical clustered architectures with single-dispersion rod nanostructures. Keywords: Green Synthesis, Nickel Oxide Nanoparticles, Roselle Leaf Extract, Crystalline Structure, Morphological Characterization]]>
