The inhibitor effect of Agave Americana Extract (AAE), on mild steel corrosion in 0.5 M H2SO4, was investigated by potentio dynamic polarization technique and Electrochemical Impedance Spectroscopy (EIS). The inhibitor concentration effect on the corrosion process was studied. AAE acts as a mixed type inhibitor, and the inhibition efficiency increases according to the inhibitor concentration's increase up to 81.87% at 2000 ppm. The inhibitor adsorption process is spontaneous and follows the Langmuir isotherm, as well as its molecules are both physisorbed and chemisorbed on steel surface. The inhibitor film formation was confirmed by ATR-FTIR and SEM analyses.