This research aims were to produce and study properties of fiber boards from oil palm empty fruit bunch fibers mixed with Water hyacinth fiber, by using 13% adhesive substances comprising urea formaldehyde (UF) and polymeric diphenylmethane diisocyanate (PMDI) resins. The boards had a density of 400, 600 and 900 kg m–3 and a thickness of 15 mm. Physical and mechanical properties tests were performed according to industry standards, TIS 876-2547, ASTM D 1037-1999 and ASTM D 256-2006a. The physical properties investigated were moisture content, water absorption and thickness swelling of the plates. The results revealed that plates with high density had low moisture content, low water absorption and low thickness swelling. PMDI resin provided the best adhesive quality. For the mechanical properties investigation, modulus of rupture, modulus of elasticity, the tensile strength perpendicular to the surface, impact strength, the nail and screws holding power were covered. It was found that the higher density they had, the better mechanical properties they owned. The PMDI-based boards with 900 kg m–3 density achieved the best mechanical properties. They can highly possibly be used instead of wood.