My research program and research institution are embedded in French neo institutional analysis conduced by Claude Menard, Eric Brousseau & Jean Michel Glachant. My PhD tries to make clearer the different ways electricity reforms in Europe are produced with mainly a European revisited Mary Shirley World Bank [1995] framework. In my PhD four problems intend to be solved: The first one tries to make clearer what is an electricity reform? In order to deals with this problem I try to show all the dimensions of this market creation in traditionally integred firms. According mainly to the work of P. Joskow I show that the choice of electricity reform is a bet in term of transaction cost analysis. The market reforms want to heavily reduce costs of production by introducing innovations and new investments. But this market reforms induce a higher level of transaction cost in coordination of electricity activities. The second tries to define the attractiveness of electricity reform in Europe according to the different stakeholders. In doing so, I intend to show that this different forms of attractiveness gives a sort of Path dependencies of national reforms in Europe. The third problem in my research program deals with the feasibility of electricity reform in Europe. The huge diversity of institutional environments in the countries studied from United Kingdom to the German case need to introduce an analytical framework able to show the relation between centralisation of powers and the way the reform is produce. In this point, I show that more the powers are centralised and more the reform is vertically imposed, and more the powers are decentralised more the reform is negotiated with all the stakeholders identified in the second point. The last problem deals with the problem of credibility of the new institutional arrangement introduced to manage the sector. I define the problem of credibility as a trade off between stability of rules and flexibility of decisions according to unknown problems issued from exogenous chocks or endogenous problems embedded in the new regulatory framework Spiller [2002]. This trade off needs to introduce in the definition of credible institutional arrangements two different mechanisms: the first one has the goal to solve the problem of stability by introducing or enforcing existing safeguards structures; the second deals with the solutions of adaptation problems of the regulatory framework. I show that this to dimension has to be built in a complementary fashion to produce an effective regulatory structures.