Inhibitive effect of Linum Usitatissimum (LU) on the acid corrosion of mild steel in 1M H2SO4 solution was studied by weight loss, Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Linum Usitatissimum effectively inhibited the corrosion of mild steel with efficiency ranges from 85.7 to 95.5 % for LU concentrations from 80 to 1200 ppm. EIS showed that the charge transfer governs the corrosion process of mild steel in 1M H2SO4 solution. Adsorption isotherm study was performed using weight loss measurements where Langmuir and El-Awady models were applied on data to investigate the model of adsorption. Corrosion inhibition was also tested at different temperatures to measure the thermodynamic parameters; ΔG°, ΔH°, ΔS° and Ea. Inhibition was suggested to occur due to adsorption phenomenon and data obey the Langmiur model. Thermodynamic study reveals that adsorption is exothermic–physical process driven by entropic factors. The morphology study using SEM confirms the electrochemical investigation where the corrosion resistance increases with increase of inhibitor concentration.