The research area of Wireless Sensor Networks (WSN) is growing rapidly. WSN technology is making entrance into new application areas, for example industrial control and Critical Infrastructure (CI) environments. Energy efficiency is a highly prioritized goal of communication protocols and application design for WSN. However, the usage of WSN in both industrial and CI environments are starting to require more and more complex applications. In this paper, we present a new low-power wireless sensor platform nicknamed TinyMulle. The TinyMulle architecture consists of a 16-bit micro controller with a maximum speed of 20 MHz and 31kB of RAM, an IEEE 802.15.4 compatible radio transceiver and several on-board sensors. Even with its small physical size, it is a powerful node capable of meeting the ever more demanding requirements of today's applications. Power consumption experiments indicate that operational lifetimes for TinyMulle in the range of months to years is feasible. The support for TinyOS enables the new platform to reuse existing software components developed for other sensor platforms