DIESIS proposes to establish the basis for a European modelling and simulation e-Infrastructure based upon open standards to foster and support research on all aspects of critical infrastructures with a specific focus on their protection. DIESIS will perform a thorough conceptual design study in order to prepare the establishment of such a research e-Infrastructure.In particular, DIESIS will: a) analyse in detail the requirements for the research e-Infrastructure coming from researchers, industrial stakeholders, decision makers and governmental organisations; b) develop an extensible ontology and communication protocols in order to define a standard for interoperable simulations in the field of critical infrastructure protection; c) provide concepts enabling interoperability among heterogeneous and distributed modelling and simulation technologies; d) design an ICT architecture for a distributed European e-Infrastructure on top of existing GRID approaches in order to support federated, interoperable simulations and research on critical infrastructure protection; e) implement a prototype of such an infrastructure as a proof of concept; f) assess the feasibility (scientific, technical, and financial) and the potential impact (scientific and technical) of such an e-Infrastructure.While the main focus of the project is on research in the critical infrastructure domain the developed concepts, protocols and technologies will be applicable much more broadly. In principle, these should be applicable to all kinds of research where federated simulation is useful.By providing the design and the evaluation of the feasibility DIESIS is the first step towards a European e-Infrastructure for research in the important and emerging field of critical infrastructure protection that will lead to more dependable, resilient and secure infrastructures to the benefit of all European citizens and European society and economy at large.