The WSAN4CIP project focuses on the ICT theme and covers the Objective ICT-SEC-2007.1.7 of the joint call between the ICT Theme and the Security Theme on Critical Infrastructure Protection. The goal of this project is to increase the dependability of Wireless Sensor and Actuator Networks (WSANs) significantly beyond the current state of the art. By that WSAN will become a "technology building blocks for creating, monitoring and managing secure, resilient and always available information infrastructure. Wireless Sensor and Actuator Networks (WSAN) provide an ideal means to achieve the envisioned improvement on CI reliability. The highly distributed nature of WSAN boosts their ability to survive malicious attacks as well as accidental failures and makes them dependable in critical situations when the information is needed to prevent further damage to critical infrastructures. As WSANs are inexpensive to lay out and self-organizing, an emergency extension of the WSAN as a first reaction is possible. Exploiting these features makes WSANs an ideal mechanism to improve situation awareness of managing tools for critical infrastructures. But current state of the art WSANs are not sufficiently dependable. In order to remedy this we will tackle the following challenges: 1.      Improving sensor node protection to improve their dependability 2.      Investigation of dependable networking approaches 3.      Investigation of dependable services running on top of WSAN that ensure graceful degradation in case of failures. In order to allow an easy use of WSAN and to make them really a technology building block we will investigate and develop Methodologies for designing WSAN according to specific requirements and we will define an open interface to ensure interoperability with existing CI management applications. We will demonstrate the appropriateness of our approach by applying it to two representative CI applications, in the area of power generation and distribution management system.