The paper addresses an analysis of OSGi in the context of building modular middlewares for the Internet of Things. The Internet of Things (IoT) is an emerging approach to development of intelligent infrastructures combining various devices through the network. OSGi is a framework providing a number of specific mechanisms intended for building modular, fine-grained and looselycoupled Java applications. Although a number of works have been devoted to OSGi, and several OSGi-based middlewares have been designed for the IoT, they do not thoroughly utilize mechanisms of OSGi. In this paper rich OSGi functions are analysed in terms of development middlewares for the IoT. An example implementation of the system illustrates the presented considerations.