A simple anodization method followed by an annealing treatment was employed to synthesize a porous nickel oxide (p-NiO) film from nickel foil. Ethylene glycol containing water and NH4Cl was used as the electrolyte matrix leading to the formation of a nanotube-like NiO structure. The anodization process was systematically optimized by varying the applied potential and electrolyte composition, revealing a direct correlation between NiO morphology and electrochemical performance. Fourier-transform infrared spectroscopy confirmed the successful formation of NiO, while scanning electron microscopy images displayed distinct morphologies and porosity resulting under different anodization conditions. An optimum anodization potential of 30 V in ethylene glycol containing 0.5 wt% NH4Cl produced uniformly distributed pores with the highest porosity of 6.14 ± 0.60 %, enhancing the electro-active surface area approximately two-fold. Additionally, this study investigates the possible formation of nickel-based complexes dissolved during the anodization process, providing insights into the mechanistic pathways governing NiO formation. The synthesized p-NiO exhibited excellent catalytic activity in the urea oxidation reaction, achieving a maximum signal-to-background ratio of 15.32, approximately five times higher than that of the unmodified nickel foil. Further evaluation as a non-enzymatic urea sensor demonstrated a low detection limit of 2.5 μM with high selectivity against glucose, Ca2+, and Cu2+, and a reproducibility of 4.83 % relative standard deviation (RSD) over seven repeated measurements. p-NiO was successfully applied for urea detection in human urine, highlighting its potential for medical diagnostics and environmental monitoring. These findings offer a new perspective on electrolyte selection and anodization strategies for microporous NiO synthesis, distinguishing this work from prior anodization studies. © 2025 Elsevier B.V.