Purpose: To investigate whether hydrogen-oxygen (67%–33%) therapy could improve the postoperative pulmonary function, recovery, complications, inflammatory reactions, and oxidative stress in patients undergoing lung surgery.Methods: We performed a prospective, randomized, single-blind, controlled clinical trial between December 2020 and December 2021. Eligible patients received either a lobectomy or sublobar resection. Postoperatively, they had 2-hour hydrogen-oxygen therapy (group H) or oxygen therapy (group C) daily, for three consecutive days. The pulmonary functions, recovery, pain intensity, oxygen saturation, inflammatory cytokines, and anti-oxidative markers were documented.Results: A total of 66 patients were analyzed, with 33 patients in each group. Both groups had decreased postoperative pulmonary functions, but group H had significantly better postoperative pulmonary functions than group C (forced vital capacities were 1.4±0.5 and 1.0±0.4 L and forced expiratory volumes in the first second were 1.1±0.3 and 0.9±0.3 L in group H and C, respectively (both P<0.01)). Compared to group C, group H had significantly decreased drainage volume, reduced catheter indwelling duration, shortened length of hospital stay, and lower pain intensity. Group H had statistically significantly decreased postoperative serum cytokine TNF-α and IL-6 levels and increased anti-oxidative markers compared to group C. The incidences of postoperative complications were comparable between the two groups. Conclusion: Hydrogen-oxygen therapy could improve postoperative pulmonary functions, decrease pain intensity, accelerate recovery, and shorten the length of the hospital stay in patients who have undergone lung resection, which may be related to its anti-inflammatory and anti-oxidative effects. Trial registration: The Chinese Clinical Trial Registry (registration number ChiCTR2100042101),the date of registration was January,13,2021.