The development process of hypermedia applications implies very specific problems mainly related, first, to the use of navigational structures, interactive behaviours and multimedia compositions, and second, to the fact that are used by users with different levels of knowledge and skills, and also different security levels. This paper present a design environment, AriadneTool, that allows a designer to model a hypermedia application, to validate such a design and to generate dynamically XML + SMIL implementation templates. This environment is based upon the Ariadne method which offers a set of integrated activities to model hypermedia applications in a systematic and iterative way. A practical example is shown to illustrate the use of the tool in the development of a hypermedia application.