By using cyclic voltammetry composites of polyaniline and carboxymethylcellulose were synthesized on AISI 304 from a 1M H3PO4 aqueous solution containing 0.2M aniline and CMC varying from 0.1 to 1% wt. The characterization was performed by different techniques and it was possible to observe that increasing the CMC content, a more packed structure is promoted, compared to the granular structure of PAni films. The evaluation of the composites to protect the substrate against corrosion showed that in doped and undoped states the composites present effective corrosion protection of AISI-304 and that the composition of the films changes after corrosion tests.