BACKGROUND: Sepsis-associated encephalopathy (SAE) leads to increased mortality. Hydrogen (H METHODS: A mouse sepsis model was established via cecal ligation and puncture (CLP). 67% H RESULTS: HCH inhalation improves 7-day survival and cognitive function in septic mice and reduces brain tissue damage, proinflammatory cytokine levels, and phosphorylated tau levels. These effects were reversed by a mitophagy inhibitor. HCH significantly improves mitochondrial function, enhances PINK1/Parkin-mediated mitophagy, and reduces the activity of the STING-TBK-IRF3 pathway in brain tissue. CONCLUSIONS: HCH inhalation effectively improved the survival rate of septic mice, alleviated SAE, and reduced tau phosphorylation. The mechanism may involve HCH enhancing PINK1/Parkin-mediated mitophagy, which inhibits the activity of the cGAS-STING-IRF3 pathway, thereby reducing neuroinflammation.