Two types of corrosion inhibitors are studied in laboratory tests simulating batch and continuous treatment methods. Type I is an inhibitor which is adsorbed on the corrosion prcduct layer and forms an inhibitor film. Type II reacts with the corrosion product layer to form a protective film. With both inhibitors, the protection offered by continuous treatment at 100 to 1000 ppm inhibitor compares favorably with batch treatment using neat or 10% solutions of inhibitor. The results show batch treatment of gas phase and liquid phase coupons with a 50% solution of Type I inhibitor gives optimum protection. The treatment gave 91% protection on the liquid phase coupons end only 70% protection on the gas phase coupons, indicating the gas phase coupons are more difficult to inhibit. Batch treatment with neat Type II inhibitor gave better protection than treatment with 10% solutions of the inhibitor in methanol, crude oil or resid oil. The Type II inhibitor at 100 ppm in a continuous application gave as much protection as batch treatment with neat cr 10% solutions of the inhibitor in solvents. Keywords: corrosion inhibitor, rotating cylinder electrode, continuous treatment, batch treatment, autoclave, CO2 corrosion