Arundo donax is a cane species with high growing productivity, and it is becoming an important source of biomass. The main objective of this study was to obtain fibreboards with high mechanical performance from A. donax without any added adhesive. Boards made without adhesive are free from formaldehyde emissions and consume no fossil resources. The characteristics of the obtained boards depended on the original material, steam explosion pre-treatments, and forming conditions (pressure, temperature, and pressing time). Production parameters were optimized. The effect of forming pressure on the physical and mechanical properties density, elastic modulus (MOE), modulus of rupture (MOR), tensile strength perpendicular to the faces (IB), thickness swelling, and water absorption of the obtained boards was studied. The European Norms (EN) methodologies were used to test the board specifications. Density, MOE, and MOR were modelled by a double reciprocal function. TS and WA were modelled with a reciprocal function in X. The boards obtained met and sometimes exceeded the requirements of these standards for the most demanding structural use.