Internal social media (ISM) has been extensively used in organizations to support communication, collaboration, and information sharing. Therefore, research about ISM in organizations also increased in recent years, but very few studies discuss ISM in government organizations. This study aims to provide an overview of ISM implementation in government organizations and to examine a proposed ISM acceptance model with the factors that influence it. The model was built by modifying the unified theory of acceptance and use of technology 2 (UTAUT 2), obtaining seven hypotheses which were tested using Structural Equation Modeling - Partial Least Square (PLS-SEM) analysis. The results show that ISM in several government organizations in Indonesia have not been used optimally and lack of user participation. They need to improve the user interface, update the content, add features that are relevant to user needs, and overcome system access problems. Then, from the seven hypotheses formulated, only two were accepted, which shows that performance expectancy and hedonic motivation have a significant positive effect on the intention to use ISM in government organizations. Furthermore, the results of this study can be used as a foundation for decision-making in ISM implementation in government organizations.