The Miscanthus X giganteus (MXG) presents many advantages (high yield, perennial crop, easy harvesting...) so it can be considered as a good candidate in terms of renewable energy sources. Several works have been carried out and were devoted to the MXG, especially in the agricultural field, but this study is the first which deals with gasification in order to produce syngas. The catalytic steam gasification of MXG in a fluidised bed reactor into presence of olivine based catalysts was investigated. Three parameters were studied, the temperature (800 degrees C and 900 degrees C), the pellets size (6 mm and 8 mm) and the nature of catalyst (olivine and Ni/olivine). Noteworthy is the efficiency shown by the Ni/olivine at 800 degrees C. which leads to the production of 1.7 m(3) kg(-1) daf of gas, containing 50% of H-2. Ni/olivine catalyst was characterised by XRD. TPR and SEM-EDX in order to monitor its structural changes during the process. Moreover, a solvent system of tar recovery was tested, which allows to obtain a more representative set of the whole tars. Then, the tars composition was determined by GC/MS. The identification of different compounds shows the presence of different PAHs, in majority naphthalene. (C) 2011 Elsevier B,V. All rights reserved.