The use of natural fibers to reinforce composite materials has been gaining considerable notice in many industrial fields. This is mainly due to environmental restrictions, which impose legal requirements related to the use of synthetic products, aiming at the reuse and replacement of non-renewable raw materials, which cause less damage to the environment. Natural fibers are biodegradable, renewable resources with very attractive properties and morphology. Among them, new categories of fibers are being investigated, as the case of piassava fiber, from the palm of Attalea funifera Martius. Its long, smooth, sturdy and waterproof textured fiber has similar mechanical properties to the coconut fibers widely used in the industry. One of the challenges in using these fibers as reinforcement in composite materials is to improve the interaction between fiber and polymer matrix, since the natural fibers are hydrophilic and the matrices are hydrophobic, developing weak interfaces. In some cases, specific chemical treatments (eg the mercerization method) can improve this interface by removing part of the lignin and cellulose from fibers, making the rough surface compatible with the polymer matrix. In this work, several parameters were evaluated through MEV, microCT, FTIR and confocal laser scanning microscopy (CLSM) of piassava fibers, before and after mercerization with 10 percent by weight aqueous NaOH solution. The analyzes allowed to evaluate that the alkaline treatment promoted a deep cleaning on the surface of the fibers, removing protrusions of silica from the vegetable, besides removing lignin, hemicellulose, cellulose, waxes and other impurities, causing tissue defibrillation. Also, it was able to increase the surface area, roughness and porosity of the fibers after chemical treatment.