Abstract Weight loss and Density Functional Theory (DFT) methods were used to study the corrosion inhibition of 5-methyl-2H-imidazol-4-carboxaldehyde and 1H-Indole-3-carboxaldehyde on mild steel in acid medium. The values of thermodynamic parameters such as free energy of adsorption (ΔGºads), adsorption equilibrium constant (Kads), adsorption entropy (ΔSºads), adsorption enthalpy (ΔHºads) and activation energy (Ea) were calculated and discussed. The adsorption process on mild steel surf...