The primary objective of this study was to investigate the effect of moisture absorption on the mechanical degradation of hybrid Napier/glass-epoxy composites. The hybrid Napier/glass-epoxy composites plates were produced by the vacuum infusion method using epoxy resin as a matrix. The hybrid composite specimens were tested after following 50 h of water immersion. The moisture content decreased as the glass fibre content increased. The wet and dry hybrid composite samples were subjected to tensile tests. The incorporation of the glass fibre into the Napier grass fibre-epoxy composites enhanced their tensile strength and tensile modulus. The tensile strength and tensile modulus of the hybrid Napier/glass-epoxy composites (24/6-70 vol%) were 43 MPa and 3.2 GPa, respectively. However, the tensile strength and tensile modulus properties highly degraded under wet conditions.
