**Abstract**

Biopolymers-based compounds were used by different manners for metal protection toward corrosion phenomena, namely via inhibiting additive and coating strategies. In the last decade, the application of these compounds or their chemically modified forms as effective replacements for toxic inorganic and organic inhibitors attracts more attention. Additionally to their intrinsic chemical stability, biodegradability, eco-friendly, low cost and renewability, biopolymers set were shown the remarkable effect to control the dissolution of several metallic materials in various corrosive environments. Among a large variety of available biopolymers, chitosan and its functionalized form, as well as its nanoparticle composites, have been reported and widely used as good anti-corrosion compounds for different metal/medium systems. In this context, the current chapter aims to shed more light on this subject.

**Keywords:** corrosion, chitosan, chitin, inhibitor, metal, solution, coating, composite
