Résumé : Model Driven Engineering (MDE) advocates the use of Model Transformations (MT) in order to automate repetitive development tasks. Many different model transformation languages have been proposed with a significant development cost as classical elements like expressions, statements, . . . must be developed from scratch in each language. The Tom language is a shallow extension of Java tailored to describe and implement transformations of tree based data-structures. Expressions, statements and many other elements rely directly on Java constructs and are thus almost costless. A key feature of Tom allows to map any Java data-structure to tree based data abstractions that can be accessed by pattern matching. In this paper, we present how this approach can be extended in order to describe model transformations, and in particular EMF (Eclipse Modeling Framework) based model transformations. This allows to provide a low cost transformation language both on the language tool development and on the developpers training side.