The effect of extract of Delonix regia on corrosion inhibition of mild steel in aqueous 0.1 M sulphuric acid was investigated by potentiodynamic polarization (PDP), scanning electron microscopy (SEM) and Fourier transformed infra-red spectroscopy (FTIR) techniques. The inhibition efficiency is found to increase with increase in concentration of the extract. Polarization measurement indicates that Delonix regia acts as a mixed type. The inhibition is assumed to occur via physical adsorption of inhibitor molecules on metal surface, which obeys Langmuir adsorption isotherm. The negative values of ?Gads show that adsorption of inhibitor on surface of the mild steel is spontaneous. Results from the Gas Chromatography – Mass Spectroscopy (GCMS) analysis indicated that DRLE has some phytochemicals with hetero atom(s) and π electrons in their aromatic or long carbon chain which may have facilitated the transfer of charge from the inhibitor’s molecule to the charged metal surface, hence inhibiting the corrosion process of the metal. SEM and FTIR studies confirmed the adsorption of inhibitor molecules on mild steel surface.