Metol, a common photographic and hair-dye agent, poses significant environmental and health risks upon release into water systems, requiring sensitive and reliable detection tools. To meet this need, we developed a highperformance electrochemical sensor based on a hybrid nanocomposite of nickel oxide-iron nitride anchored on carbon microspheres (NiO-Fe3N/CMS). Material characterization played a central role in understanding its superior function: XRD and XPS confirmed the successful formation of crystalline NiO and Fe3N phases and their electronic interaction. Raman spectroscopy verified the graphitic structure of the CMS support and the presence of metal oxide/nitride bonds. BET analysis showed that all materials possess Type IV mesoporous structures. Notably, the NiO-Fe3N/CMS composite exhibits a BET surface area of 34.7 m2/g, with the highest pore volume (0.1605 cm3/g) and largest pore size (18.49 nm) compared to the individual components. The NiO-Fe3N/CMSmodified electrode exhibited the lowest charge-transfer resistance (198.25 Omega) and largest electroactive surface area (0.0981 cm2) among all tested electrodes, enabling ultrafast electron transfer. Consequently, the sensor delivered outstanding analytical performance for MT detection: an ultra-wide linear range (0.01-1836 & micro;M), high sensitivity (0.3581 & micro;A & micro;M- 1), and a remarkably low detection limit of 0.0046 & micro;"M. It also demonstrated excellent repeatability, reproducibility, and long-term stability. When applied to real water samples (tap, pond, and river water), recovery rates ranged from 97.8% to 99.9%, confirming its accuracy and practicality. This work highlights how deliberate material design and thorough characterization can yield robust sensing platforms for onsite environmental monitoring."