The inhibition of mild steel corrosion in a 2.5 M H2SO4 solution by 4,4-dimethyl-3-thiosemicarbazide (DTS) was studied at 30 degrees C using potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Quantum chemical parameters were calculated for DTS using PM3-SCF method. The molecular dynamic method was performed to simulate the adsorption of the DTS molecules on Fe surface. Results showed that DTS performed excellent as inhibitor for mild steel corrosion in a 2.5 M H2SO4 solution and indicated that the inhibition efficiencies increase with the concentration of inhibitor. Theoretical results indicated that DTS could adsorb on the mild steel surface firmly through heteroatoms. (C) 2011 Elsevier B.V. All rights reserved.