Corrosion resistance behaviour of mild steel was evaluated in mineral acid using castor seeds as inhibitor. The potentiodynamic polarization measurement was carried out at room temperature for experimental data. The electrochemical experiment was carried at varying concentrations of the inhibitor. The extrapolation of the Tafel curves gave the corrosion rate and explained other parameters. The results obtained showed the susceptibility of mild steel without the inhibitor in mineral acids and its protective inhibition when different concentrations of castor seeds extract were used as inhibitor in the mineral acid environment.