This study examines the corrosion inhibition of copper in aerated H2SO4 solution using 5-methyl, 5-phenyl, and 5-methyl-2-phenyl derivatives of 2,4-dihydro-3H-pyrazol-3-one (Py) through electrochemical techniques, gravimetric method, SEM, DFT and Monte Carlo simulation. The results showed that these compounds exhibited good inhibition efficiency, increasing in the order: Py II (84.9 %) < Py III (87.9 %) < Py I (90.1 %) at 10 mM. The protection efficiency improved with higher inhibitor concentration and decreased with rising temperature. Thermodynamic parameters for the inhibition process were calculated, with Hads 0 values of -17.76±0.607, -15.8±0.101 and -16.24±0.118 kJ mol -1 for Py I, Py II and Py III, respectively, confirming the exothermic nature of adsorption. The adsorption followed the Langmuir isotherm and occurred physically and spontaneously. Monte Carlo simulations indicated that PYs adsorbed in a parallel configuration, provide better coverage of the metal surface with high adsorption energy. SEM confirmed formation of a protective layer. Based on experimental and theoretical data, pyrazolone derivatives are recommended as corrosion inhibitors for copper in H2SO4 media.