PurposeThe purpose of the present study is to build a research model to study how the use of different enterprise social media platforms affects employees' relationship capital, and the moderating role of innovation culture is also examined.Design/methodology/approachStructural equation modeling was performed to test the research model and hypotheses. Surveys were conducted in an electronic commerce company in China that uses different social media platforms, generating 301 valid responses for analysis.FindingsFirst, private social media used for work-related purposes can contribute to employees' relationship capital, and public social media QQ used for work-related purposes can contribute to employees' communication quality. WeChat used for social-related purposes has a positive effect on employees' information exchange. Second, innovation culture acts as a positive moderator between work-related media use and employees' information exchange, while innovation culture acts as a negative moderator between social-related WeChat use and employees' information exchange. Third, innovation culture acts as a positive moderator between work-related QQ use and employees' trust, while innovation culture acts as a negative moderator between social-related QQ use and employees' trust.Originality/valueFirst, this paper contributes to the information system (IS) social media literature by studying the effect of the use of different enterprise social media platforms used for different purposes on employees' relationship capital. Second, the authors contribute to relationship capital theory by clarifying that use of public and private social media platforms for social- and work-related purposes is an important driver of the formation of employees' relational capital. Third, the present study also contributes to enterprise social media literature by confirming that innovation culture acts as a different moderator between use of different enterprise social media platforms and employees' relationship capital.