Background: Persistent vegetative state (PVS) is a devastating and long-lasting clinical condition with high morbidity and mortality; currently, there are no available effective interventions. Case summary: We report the case of an 11-year-old boy with PVS caused by severe intracerebral bleeding in the left hemisphere following anticoagulation treatment. The patient’s PVS severity showed no notable improvement after 2-mo neuroprotective treatment and rehabilitation, including nerve growth factor and baclofen, hyperbaric oxygen, and comprehensive bedside rehabilitation therapies. Daily inhalation treatment (4-6 h) of high-concentration hydrogen (H2) gas (66.6% H2 + 33.3% O2) was provided. Surprisingly, the patient’s orientation, consciousness, ability to speak, facial expressions, and locomotor function were significantly restored, along with improvements in essential general health status, after H2 gas inhalation treatment, which was consistent with stabilized neuropathology in the left hemisphere and increased Hounsfield unit values of computed tomography in the right hemisphere. The patient finally recovered to a near normal conscious state with a Coma Recovery Scale-Revised Score of 22 from his previous score of 3. Conclusion: Phase 1 clinical trials are needed to explore the safety and efficacy of H2 gas inhalation in patients with PVS.