The purpose of our communication is to present first results from a current research on the development and usage of open archives in France. This study aims to gain empirical insight in usage patterns of freely available scientific items deposited in open archives, especially of non-commercial material, e.g. grey literature, mostly not distributed through other channels. We present a state of the art of published empirical data, standardization, research projects etc., together with a survey on the development and the usage of French open archives, based on open source methods and investigation. The usage of grey literature in open archives is a recent field of professional and scientific interest. So far, little has been published on usage of open archives, and even less, on usage of deposited grey literature. Nevertheless, there are some promising new initiatives and projects and first empirical data. Our communication will combine review, quantitative and qualitative survey data and case study in order to provide a realistic insight into this emerging field. Expected results: Empirical data allowing for first comparison between different archives and document types. Awareness on the scientific but also professional and economic interest of these data. A contribution to standardization (recommendations on data production, delivery and analysis).