With strong computing power and efficient data networks, new mobile phones are sophisticated enough for smoothly surfing the internet and conducting electronic commerce as on the desktop computers, there should have significant opportunities and growth of mobile commerce. However, the user acceptance of m-commerce is below expectation (Harris et al., 2005). Researches of the user acceptance of m-commerce have proven the positive user adoption determinants based on the user acceptance models of information systems (IS), but only few explore the negative adoption factors. This paper extends the unified theory of acceptance and use of technology (UTAUT) model for the study of the negative emotion and behaviour that affects the user acceptance of m-commerce. The extended UTAUT model aims to help m-commerce service providers to understand both the positive and negative factors that can significantly explain user adoption intention and use behaviour so that they can adjust their strategies for providing successful m-commerce services. It also provides an extended base for further research on the user acceptance models of new IS.