As for most other complex software systems, Military Communication and Information Systems (CIS or C3I Systems) raise numerous software engineering problems such as design, development, requirements compliance, evolution and maintenance. To these problems, object oriented methods and tools claim to bring a solution. But beyond the current fashion of the object oriented technology in the software industry, is this new approach mature enough for developing large and industrial strength applications such as CIS? This article presents the preliminary results from a pilot project undertaken by the “Centre de Maquettage des SIC” of the French Ministry of Defense, aiming at assessing the promises of object orientation. A both theorical and pratical object oriented technologies state of the art is first presented, followed by the findings of our experiment, still under progress, in which an object oriented methodology based on prototyping and various object oriented tools have been applied together on the development of a real CIS. Those findings deal with methods and tools as well as methodology and people.