Resumo. BACKGROUND: Environment with low oxygen availability can have detrimental effects on cognitive abilities. Nevertheless, exercise can have beneficial effects on cognitive abilities, and these effects may vary with the environment. Therefore, it is important for the performance of individuals to understand the uncertainties about the conditions that can compromise cognitive function. AIM: To identify which hypoxic conditions can cause attention disturbance. METHOD: A total of fourteen volunteers (24.4 ± 3.9 years old; 82.8 ± 14.9 kg weight; 178.6 ± 7.9 cm height) participated in this single-blind, randomized, with a within-subjects design study. Participants completed an adapted version of the Stroop Color-Word Test (SCWT) before and after exposure in normoxia and hypoxia (FIO 2 = 0.209 and 0.138, respectively), in two conditions: (i) at rest for 30 minutes and (ii) under exhaustive effort. The data were analyzed using a Bayesian statistical approach. RESULTS: SCWT performance under hypoxic conditions showed no difference compared with exposure moments (before and after), as well as showed no difference compared with normoxic conditions. The SpO 2 in hypoxic conditions was significantly lower than in normoxia conditions, unlike HR, which revealed no difference. The hypoxia dose at rest and under exhaustive effort was 2.5 and 0.8 %.h, respectively. CONCLUSION: Despite a drop in SpO 2 and with hypoxia doses equivalent to 2.5 and 0.8 %.h, it was not possible to confirm differences in the indices related to attention. This indicates the existence of a minimum hypoxia dose to affect cognitive performance.