The principal purpose of the paper is to show the help that Market Research Techniques gave to the decision makers of the biggest privatisation ever conducted in Spain. The authors start by describing the company, the aims of the privatisation and the marketing approach, with a description of the strategy used. The paper describes the proposal from the Research Institute and the design of the micromodel used for the forecast of demand. The validation of results plus a number of factors affecting the prediction are also discussed. The decisions taken in light of the market research results are also described in the paper.