Exposure to chronic hypoxia induces behavioral and mood disturbances and alterations in cognitive functions. We examined the relationships of personality traits, including trait-anxiety, with performance in binary visual reaction time, psychomotor ability, and mental efficiency, using the psychological database of the ‘Everest-Comex 97’ experiment, which consisted in a 31-day simulated climb in a hypobaric chamber from sea level to 8,848 m altitude. Analysis yielded a significant positive correlation between the climbers' mean reaction time at hypoxic conditions and preclimb scores on trait-anxiety (as assessed by Spielberger's State-Trait Anxiety Inventory) and further significant negative correlations with both Factor A (reserved-outgoing) and Factor G (expedient-conscientious) of the Cattell Sixteen Personality Factor Questionnaire. In contrast, no significant correlation was found between the climbers' mean psychomotor performance and mental efficiency with personality traits, including anxiety. These findings agree with those of previous studies: (i) anxiety could mediate stimulus-response tasks but not more complex tasks requiring strategic processes, (ii) individuals with personality traits such as ‘reserved’ and ‘expedient’ could have slight advantages in processing information on stimulus-response tasks. Limitations in study design are also discussed.