Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Cellulose whiskers were obtained by means of sulfuric acid hydrolysis of curaua fibers. Before hydrolysis, the natural fibers were treated with an alkaline solution to remove the non-cellulosic content. Fiber degradation evolution and cellulose whisker formation were analyzed by structural and morphological analysis. The original fiber structure underwent a fragmentation mechanism after being exposed for 3 min to sulfuric acid. Cellulose whiskers were lixiviated from the fiber surface after 10 min of hydrolysis, developing two scenarios: one where the whiskers became unattached from the original fiber, and the other which remained attached. The cellulose whiskers presented a needle-like geometry with an approximate diameter of 11 nm and average length of 185 nm, after 30 min of acid hydrolysis. Based on microscopic characterization, a schematic representation of the morphological evolution of the cellulose fibers submitted to acid hydrolysis is proposed.19411991207Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)