Revision with unchanged content. Sensor motes are small devices with sensing, computing and wireless communication capabilities. Such devices form a Wireless Sensor Network (WSN) which can be used for many applications like gathering of environmental data and even monitoring enemy activity on a battlefield. In order to achieve this efficient ad-hoc routing protocols must be used. Such routing protocols are of prime research interest. There exist many different approaches most of which are studied through simulation only. At the same time real hardware platforms for this research become widely available and affordable. In this book a real world environmental monitoring task is taken and a complete WSN application for this task is developed. As hardware platform Crossbow Technology's Cricket motes are used. They are programmed using TinyOS operating system and the NesC language. The usability of various state-of-the-art routing mechanisms for the specific application is discussed. Finally some of these are selected and implemented for use in the developed WSN application. The performance of the different available routing protocols is then measured and compared through actual deployment of the WSN.