PurposeInterpersonal interaction can influence consumers’ purchase intention in social commerce (s-commerce). This paper aims to identify interpersonal interaction factors as well as the mediating effect of relationship quality between interpersonal interaction factors and consumers’ purchase intention in s-commerce.Design/methodology/approachThis study explores new dimensions of interpersonal interaction in s-commerce by integrating interaction between consumers and online vendors and that between consumers and online recommenders in s-commerce. An online questionnaire was used to collect the data, and partial least squares structural equation modeling (PLS-SEM) was employed for data analysis.FindingsThe results indicate that interpersonal interaction factors of both online vendors and online recommenders positively affect swift guanxi and initial trust between consumers and online vendors. Swift guanxi and initial trust positively affect consumers’ purchase intention. Initial trust partially mediates between interpersonal interaction factors and purchase intention while swift guanxi does not mediate between perceived similarity of online recommenders and purchase intention.Practical implicationsThe findings can be used to guide vendors in s-commerce platforms to make good use of platform features to improve interpersonal interaction. Meanwhile, s-commerce platforms should be enhanced with efficient interaction tools to help cultivate relationship quality between consumers and online vendors.Originality/valueThis study combines social exchange theory, trust transfer theory and relationship quality theory to investigate the factors that influence swift guanxi and initial trust between consumers and online vendors, which extends the study of interpersonal interaction and enriches the dimensions of relationship quality in the context of s-commerce.