The açaí seed is an abundant byproduct of açaí productive chain, Brazil`s northern region important fruit, especially in Pará and Amazonas states. However, it has been characterized as a hygienic-sanitary inconvenience to the region big cities, respectively Belém and Manaus. The use of this material to generate high added value products depends on better knowledge of its microstructure. This work aimed to analyse açaí seeds biomass using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD) and Fourier Transform Infrared Spectroscopy (FTIR) in order to better understand its structural and chemical changes during treatment stages. For this purpose untreated, treated with H2SO4 and treated with H2SO4 and subsequently delignified with NaOH açaí seeds were used. SEM photomicrographs comparison showed that treatment with H2SO4 resulted in partial disruption of açaí seed structure, which became more evident after NaOH treatment. The crystallinity index for untreated açaí seeds was 47.05%, reducing after the treatments. FTIR provided spectra in the region of 4000 to 400 cm-1. The used techniques allowed to observe significant structure changes caused by açaí seeds biomass treatment and provided information about microstructure of the untreated material.