Biomass of Spirulina sp. LEB 18 was used (53.8 wt% protein) for protein extraction and hydrolysis. Spirulina protein concentrate (83.9 wt%) and protein isolate (91.3 wt%) were obtained from the first and second chemical extraction by isoelectric precipitation, respectively. The biomass, its concentrate, and the protein isolate were hydrolyzed in erlenmayer and in stired tank reactor (STR). The hydrolysis reactions, with Protemax 580L (5 U.mL-1) and 4% of the substrate, were maintained at 60 ° C and
180 rpm. Buffer solution pH 9.5 was used for erlenmayer reactions and the pH of the reactions in STR was automatically controlled. There was a significant difference between the degree of hydrolysis (DH) of the Spirulina protein isolate carried out in erlenmayer (69.1 %) compared to that performed in STR (78.2 %). The hydrolysis carried out in STR provided an increase in DH between the biomass (55.3%), the concentrate (67.6%), and the protein isolate (78.2%). In addition, there was an increase in productivity, since higher DH were obtained in a shorter time interval.