**Abstract**

Organic corrosion inhibitors are preferred due to its environmental friendly and effectiveness at a wide range of temperatures. The efficiency of an organic inhibitor depends on the size of the organic molecule, aromaticity, type, and number of bonding atoms or groups in the molecule (either π or σ), nature and surface charge, the distribution of charge in the molecule, and type of aggressive media. The presence of polar functional groups with S, O, or N atoms in the molecule, heterocyclic compounds and pi electrons present in the molecule also increases the efficiency of these organic corrosion inhibitors. The use of computational chemistry such as density functional theory (DFT), molecular dynamic simulation (MD), Monte Carlo (MC) simulations, and quantitative structure-activity relationship (QSAR) modeling has been applied for study of corrosion inhibition properties of organic compounds. This chapter will explain about theoretical and computational study of organic compounds as corrosion inhibitors.

**Keywords:** organic corrosion inhibitors, physisorption, cathodic inhibitors, anodic inhibitors, mixed inhibitors
