Employee motivation at work is one of the important factors which significantly impact job satisfaction, commitment, quality of work, and job performance. Organizations need to determine the best way to motivate their employees who are part of different generational groups (Baby boomers, Generation X, and Generation Y). Hens, this study was conducted to investigate the relationship between generational differences and work motivation of executive-level employees in the glass industry in Sri Lanka. Using Deci’s intrinsic and extrinsic motivation theory as the foundation, we evaluate the relationship between generational differences and employee motivation in the glass industry in Sri Lanka. At present, only three generations, the Baby Boomers, Generation X, and generation Y, are available within the organizations’ workforce. Therefore, only these three generations were used to conduct this study. The data were collected from a randomly selected sample of 70 executive-level employees who work in a leading company in the glass industry in Sri Lanka, by administering a structured questionnaire with 23 questions/statements on a five-point Likert scale. the method was used as the method of data collection. Data were analyzed using univariate analysis and bivariate analysis including correlation analysis with the SPSS 23.0 version and derived the results. According to the results of the study, there is a significant positive correlation between baby boomers and extrinsic motivation. The Pearson correlation between the main two variables of Generation "X" and intrinsic motivation, and also Generation "Y" and intrinsic motivation, was positive in executive employees in the glass industry in Sri Lanka. Positive relationships with extrinsic motivation and baby boomers were also discovered. Generation "X" and "Y" positively related to the intrinsic motivation at work in executive employees in the glass industry in Sri Lanka. In the near future, there will be a new generation in the workplace, i.e., Generation Z. As a result, management must now start understanding and developing new strategies to better prepare for Generation Z employees, as well as consider how to best integrate this next generation with their current employee workforce.