As governments across the world have decreased in perceived reliability and trust, they now need more stable and continuous tools to communicate with their citizens. In this context, many government agencies are attempting to use social media tools to communicate with the public and promote citizen's trust. But, few studies have investigated the critical factors and antecedents of trust in government under social media context. Thus, this study empirically analyzes the antecedents and formation of citizen trust and expansion in actual citizen patronage behavior deploying structural equation model. The survey data was obtained from Korean population who used government's social media service. The results indicate that the formation of citizen trust in the government can be expanded into patronage intention toward social media and actual behavior. This study also demonstrates that factors related institutional-based trust, characteristic-based trust, and process based trust contribute to improving trust through government social media services. This study provides contribution as research that discovers the antecedents of trust in government social media use and it employs integrated perspective for the structural components of trust simultaneously. (C) 2015 Elsevier Ltd. All rights reserved.