The influence of the amount of silicate and the amount of absorbed moisture on the mechanical properties of PA6 nanocomposites is discussed. Diffusion coefficients have been determined from moisture absorption experiments and similar amounts of water were absorbed by nanocomposites with different silicate concentrations. The modulus of the nanocomposites increases with increasing amount of silicate and decreases with increasing amount of absorbed moisture. However, the ductility of the nanocomposites decreases with increasing amount of silicate and increases with increasing moisture content. A more hydrophobic modification of the particles results in a reduction of the degree of exfoliation in PA6, and consequently in a lower modulus, higher ductility and an increased diffusion coefficient compared to particles that are better exfoliated. PA6 nanocomposites can compensate for the decrease of the modulus of PA6 when water is absorbed from the environment. (c) 2005 Elsevier Ltd. All rights reserved.