The inhibition action of the Pyrazolone Derivative (PYR) on the corrosion of mild steel in 0.5 M sulphuric acid was investigated by weight loss, polarization, impedance and SEM. Results obtained revealed that PYR performed excellently as corrosion inhibitor with efficiency of 91% at 11 ppm at 298 K. Its adsorption on mild steel obeys Langmuir and Temkin isotherm. Polarization curves indicate that PYR behaves as mixed type. The value of ∆G° ads indicates the spontaneous physisorption of PYR. The SEM results confirm the presence of a protective surface layer over the mild steel surface. The reactivity of the compound was analysed through theoretical calculation.
