In this study we investigated the effects of hydrogen (H2) supplement, in the form of calcium bound H2 powder capsules, on aerobic and anaerobic cycling exercise. Trained male subjects participated in a randomized, double-blind, crossover design trial and received H2-rich calcium powder (HCP) supplement (1500 mg/day, 2.544 μg/day of H2 gas) or H2-depleted placebo (PLA) (1500 mg/day) for 3 consecutive days. Aerobic experiment: Eighteen subjects carried out a cycling incremental exercise starting at 20 watts (W) work rate, and increasing by 20 W/2 minutes until exhaustion. Blood gases including pH, bicarbonate ion (HCO3–), partial pressures of CO2 (PCO2), metabolic profile including lactate (Lac), and electrolytes including chloride (Cl–) were measured at rest and at 120-, 200-, and 240-W work rates. Anaerobic experiment: Six subjects carried out a 30 second Wingate anaerobic exercise test (WAnT) bout with a resistive load of 7.5% of body mass. Lac was then measured at 1-, 3-, 5-, and 15-minutes following the WAnT exercise. Aerobic experiment: At rest, HCP had a significantly lower pH (P = 0.048), Cl– (P = 0.011), and a higher HCO3– (P = 0.041), PCO2 (P = 0.026) compared to the PLA group. During exercise, pH decrease (supplement effect: P = 0.043) and the HCO3– increase (supplement effect: P = 0.030) continued in the HCP group. Additionally, HCP did not affect peak work load and exercise duration. And no changes were noted in Lac at rest or during exercise. Anaerobic experiment: HCP did not affect peak power output or Lac recovery following WAnT. However the average power output during exercise was significantly higher in the HCP group (P = 0.019) compared to the PLA group. HCP supplementation following 3 days of intake, slightly lowered pH during aerobic exercise, and increased average power output in the anaerobic WAnT exercise compared to the PLA group. HCP supplement might have an ergogenic effect in an anaerobic exercise setting. This study was supported by The Japan Society for the Promotion of Science, and the Ministry of Education, Science, and Culture of Japan. In addition, we received a research grant from the company ENAGEGATE Inc. and they provided the HCP supplement and placebo. However, no intercession, restrictions or agreements of any kind was imposed between parties regarding research design, results or publications.