This study reports the green synthesis of mercuric oxide nanoparticles (HgO-NP’s) using two natural phytochemicals Ferulic acid and curcumin as reducing and stabilizing agents. The formation of HgO NPs was initially evidenced by colour transitions from pale yellow to brownish red with ferulic acid and bright yellow to reddish brown with curcumin. UV-Visible spectroscopy confirmed the formation nanoparticles with ferulic acid mediated HgO-NPs exhibiting a sharp absorption peak at 320nm, while curcumin mediated synthesis resulted in a broader peak between 275-450 nm. FTIR analysis identified functional groups responsible for the formation and stabilization of the nanoparticles with prominent peaks for – OH (3450 -3510 cm-1 ) , C=O stretching (1682 cm-1 for ferulic acid and 1625 cm-1 for curcumin) and HgO vibrations (540- 550 cm-1 ).Transmission Electron Microscopy (TEM) analysis revealed that ferulic acid mediated HgO-NP’s were larger (5-50 nm)and more aggregated whereas curcumin mediated HgO-NP’s were smaller (2-20 nm) with better dispersion and more defined spherical morphology. Antibacterial studies showed enhanced activity of both types of HgONP’s against E. coli, S. aureus, B. cereus and P.aeruginosa compared to conventional antibiotic, with curcumin mediated HgO-NP’s exhibiting superior activity against P.aeruginosa. These findings highlights how phytochemical structure diversity can be utilised to tune nanoparticles properties and their potential applications in diverse fields such as biomedical, environmental and agriculutural domains