Given the dramatically aging workforce in Germany, many companies see the retention of older employees as a central challenge. Understanding the determinants of employee satisfaction is essential for promoting the employability of older workers. This study analyzes the impact of age on the relationship between job characteristics and employee satisfaction based on empirical data and the Partial Least Squares (PLS) methodology. It reveals that different factors influence the employee satisfaction of younger and older workers, and there is significant heterogeneity among older employees. Accordingly, specific HR measures for older employees are developed.