2, 3-Dihydroxyquinoxaline (DHQ) has been investigated as an inhibitor for mild steel corrosion in 0.5 MH2SO4 solution using electrochemical techniques [Galvanostatic polarization, Potentiostatic polarization and electrochemical impedance spectroscopy (EIS)] and non-electrochemical technique (weight loss). It has been found that the inhibition efficiency of the inhibitor increases with increase in concentration. The effect of temperature ranging from 298 K to 328 K on the corrosion rate have been studied and various thermodynamic parameters are calculated. Polarization studies show that investigated inhibitor is of mixed type in nature and shows a passive range at 298 K. The adsorption of the inhibitor on the mild steel surface in acid solution is found to obey the Langmuir adsorption isotherm. Scanning electron microscopy (SEM) and Atomic Force microscopy (AFM) are performed on inhibited and uninhibited mild steel samples to analyze the surface morphology and topography. Quantum chemical calculations have also employed using the semi empirical AM1 method for theoretical calculations and obtained results are found to be in good agreement with the experimental findings.