Chitosan is a biopolymer of wide application due to its characteristics and non-toxicity, presenting antimicrobial, antitumoral and cicatrizing activities. It is currently used as emulsifier, metal’s chelating, edible biofilm and fat reducer. The variation in the deacetylation degree of this polymer gives differentiated functional properties. It is mainly obtained from crustaceans, but fish scales are also a potential source of this product, despite neglected so far. The aim of this study was to develop a method for chitin extraction and deacetylation for chitosan obtaining from Nile tilapia (Oreochromis niloticus) scales. Characterization showed that chitosan was completely purified. The chitin infrared spectrum presented a characteristic larger band in the region of 3,500 cm-1, due to axial stretching vibrations of the OH group been completely purified, which disappeared in the chitin spectrum. However, a new band aroused at 1,640 cm-1 due to the NH2 deformation, which predominated over the band at 1,655 cm-1, associated to the carbonyl (C=O) that tends to decrease, as the degree of deacetylation of chitosan increases. All bands observed were similar to those described in the literature. Although the yields were lower than the averages usually reported for crustaceans, they can be improved to obtain higher yields and deacetylation.