BACKGROUND/AIM: Primary biliary cholangitis (PBC) is a chronic autoimmune liver disease characterized by bile duct destruction, cholestasis, and inflammation, often leading to fibrosis and cirrhosis. While ursodeoxycholic acid (UDCA) is the standard treatment, some patients exhibit suboptimal responses, necessitating adjunctive therapies. Molecular hydrogen (H), known for its antioxidant and anti-inflammatory properties, has shown potential in mitigating oxidative stress and immune dysregulation in autoimmune liver diseases. This case report evaluates the therapeutic efficacy of H capsules in managing PBC with elevated liver enzymes and immune dysregulation. CASE REPORT: A 44-year-old male with PBC, splenomegaly, and elevated IgG4 levels presented with acute cholestatic hepatitis. Laboratory tests revealed significantly elevated aspartate transaminase (AST) (279 U/l) and alanine aminotransferase (ALT) (183 U/l). Despite UDCA therapy, liver enzymes remained persistently high. On August 30, 2024, molecular hydrogen capsule therapy was introduced as adjunctive treatment. Over four months, AST and ALT levels declined to 95 U/l and 70 U/l, respectively, without adverse effects. Immune markers (KLRG-1, PD-1, and Tim3), previously reduced during PBC flares, normalized post-treatment. Imaging confirmed stable fibrosis, and IgG4 levels decreased, suggesting reduced autoimmune activity. The patient also reported improvements in fatigue and pruritus, enhancing overall quality of life. CONCLUSION: Molecular hydrogen capsules therapy may serve as a safe and effective adjunctive treatment for PBC, contributing to improved liver enzyme levels, immune regulation, and patient well-being. Further studies are warranted to validate these findings and establish standardized treatment protocols in autoimmune liver diseases.