In recent years, technological innovations in the fields of sensing, computing, and communication have seen unprecedented advancements. Particularly, the explosive progress in wireless connectivity has resulted in ubiquitous access of devices, software, and control strategies over wide geographical sprawls. The Internet of Things (IoT) is an emerging paradigm that can be seen as the consummation of all these highly disruptive set of technologies. Also, the industry has been shifting from application-oriented solutions towards more service-oriented abstractions. Since most large scale and critical systems of late have been designed with this IoT paradigm, thus, modeling and analyzing the reliability of IoTs becomes an emerging research challenge. In this paper, a reliability model for IoT has been presented that specifically emphasizes the service-oriented aspect. Cloud computing services have been employed as platform for leveraging computations and data storage required for Iot operations in the proposed model. The service-oriented paradigms of such systems have the cloud infrastructure as its focal point and consequently a Centralized, Heterogeneous IoT Service System (CHISS) model has been proposed. The paper also discusses a generalized methodology to evaluate service reliability of CHISS system. Case studies presented herewith include intelligent fire alarm system and smart health care system and the results presented herewith demonstrate the efficiency of the proposed model. © 2018, © 2018 Informa UK Limited, trading as Taylor & Francis Group.