This study attempted to identify the effect of inhalation of highly concentrated oxygen on reaction time during simple visual matching tasks. Nine right-handed male graduate students (23.0+/-1.4 years) participated in the study. Two subsets of simple visual matching tasks with similar difficulties were developed. The experiment consisted of visual matching tasks performed under two conditions: normal air (22.1% oxygen) and hyperoxic air (43.2% oxygen). There was a significant decrease in reaction time in the presence of 43.2% oxygen compared with the 22.1% oxygen condition. This result supports the hypothesis that hyperoxic air increase oxygen saturation level in the blood, lead to more available oxygen to the brain, thus increase the ability of cognitive processing.