The objectives of the thesis are on one hand to propose a general theoretical frame for the process of traces re-documentation concerning a computer mediated activity (by a human being), and on the other hand to implement an environment supporting this re-documentation. The first part will lean on the communicative transactions theory and the study of links between personal traces and documents in a digital context, in particular their transformation relationship (using selection, rewriting, complements/justifications adding, etc.). The resulting document, describing the traced activity, can preserve a part of traces characteristics from which it was generated (mainly temporal ones) and will serve in an exchange with itself or with other persons. The second part will aim at developing a re-documentation tool(s) for assisting the person re-documenting the traces and offering various modalities of appropriation for the resulting document. This tool will be tested in two different application contexts: the traces re-documentation of a bibliographical tool use (Zotéro) and that of the navigation in a web site of a XIXth century newspapers archive (CANU19 project, Lyon's municipal library).