Employees with organizational citizenship behavior are characterized by the attitude of people who show employees’ willingness to exceed the minimum targets set by the organization. Thus, employees will work voluntarily even outside their duties and responsibilities. This study aims to investigate the interactions between reward systems and organizational citizenship behavior, considering work satisfaction as a mediating factor. This paper employs a quantitative methodology. Thirty-eight agricultural extension employees from the Agricultural Office in Labuhanbatu Regency, Indonesia, served as the samples. SEM (SmartPLS) approach was utilized to analyze the data. The findings discovered that the reward system has a favorable and considerable impact on job satisfaction. The results also boosted that the increase in employee job satisfaction has a positive and significant effect on increasing organizational citizenship behavior. The relationship between the reward system and organizational citizenship behavior is positive but insignificant. Moreover, the study also demonstrates that job satisfaction significantly and favorably mediates the impact of the reward system on organizational citizenship behavior. Therefore, a reward policy must be implemented to satisfy employees because job satisfaction is crucial in increasing organizational citizenship behavior
