Physical exercise-induced oxidative stress and inflammation may be beneficial when exercise is a regular activity, but it is rather harmful when exercise is exhaustive and performed by unaccustomed organisms. Molecular hydrogen (H₂) has recently appeared as a potent antioxidant and anti-inflammatory molecule in numerous pathological conditions. However, its role is relatively unknown under physiological conditions such as physical exercise. Therefore, this review summarizes the current knowledge of the H₂, reducing oxidative stress and inflammation in physical exercise, reporting data from both animal and human studies.