Internet of Things (IoT) is a new emerging technology, investment on which is expected to reach more than three thousand billions dollars in 2020. The literature focus on the technical aspects of the IoT services and less attention on the behavioral studies that clarify the perception of customers about the adoption and usage of the IoT services. Consequently, the purpose of this paper is to develop a conceptual model of the adoption of IoT services. The model is built based on the theory of Technology Acceptance Model (TAM), the Unified Theory of Acceptance and Use of Technology (UTAUT) and supplemented by a critical review of nine related articles. The outcome of this paper is a conceptual framework that links the ease of use and usefulness in TAM with social influence of UTAUT and other factors such as cost, trust, IT knowledge, and security and privacy for the IoT services