A model describing the dynamic behavior of the steam pressure inside a fire-tube boiler has been obtained using system identification techniques. A complete system identification procedure has been carried out, from experimental design to model validation using a lab-scale boiler and then ratified in an industrial-scale boiler. In both cases, the identified model is characterized by a second order ARMAX structure which describes with very high precision the process under study. This model will be used for control and prediction applications. First control simulation results are also presented. Copyright © 2007 IFAC.