Background <p>Green management practices are essential for organizational sustainability, and their adoption in hospitals can help reduce environmental impact. Organizational citizenship behavior further enhances green management efforts.</p> Aim of the study <p>This study aimed to assess the effect of a green management training program on staff nurses’ organizational citizenship behavior.</p> Design <p>Quasi-experimental design with a pretest-posttest approach.</p> Setting <p>This study was carried out in Al-Ahrar Teaching.</p> Subjects <p>85 staff nurses participated in the study.</p> Tools of data collection <p>green management knowledge questionnaire, employee green behaviors scale, and organizational citizenship behavior scale were used for data collection.</p> Result <p>Significant improvements were observed in staff nurses’ knowledge of green management (16.5–89.4%), employee green behavior (5.9–64.7%), and organizational citizenship behavior (7.1–70.6%) at pre- and post- phases respectively.</p> Conclusion <p>The green management training program effectively improved organizational citizenship behavior, supporting the research hypothesis.</p> Trial registration number <p>Not applicable.</p> Clinical trial number <p>Not applicable.</p>