IEEE 802.15.4/ZigBee and TinyOS have been playing an important role in leveraging a new generation of large-scale networked embedded systems. However, based on previous experience on the implementation and use of the IEEE 802.15.4/ZigBee protocols over TinyOS, several problems (producing loss of synchronization and even network failures) emerge due to some limitations of this OS, namely related to the lack of task pre-emption and prioritization. When real-time guarantees are required, different software solutions must be used to support real-time services in such networked applications. This being our objective, we implemented the IEEE 802.15.4 protocol over ERIKA, a real-time operating system for resource-constrained embedded systems. The results attained so far, and summarized in this short paper, demonstrate that ERIKA enables reliable network behaviour and improved network performance. This paper outlines the most important aspects of the software implementation and reports compar...