Nylon-66 is a typical semicrystalline polymer that can be crosslinked using crosslinking agents and electron beam irradiation. Hybrid nylon-66-based membranes are more porous but denser compared to the pure nylon-66 membrane. Besides that, hybrid nylon-66 membranes exhibit higher water uptake and severe swelling in water. Si/nylon-66 membranes were prepared by adding gamma-aminopropyltriethoxylsilane (APTEOS). Crosslinked silica in nylon-66 membranes is confirmed with high gel content and Fourier transform infrared peaks, but XRD results showed that there is a low crystalline degree in these membranes. The thermal stability of hybrid nylon-66 membranes is also less affected by APTEOS. The crosslinking agent only improves storage modulus in hybrid nylon-66 membranes. After irradiation, it is learned that APTEOS improves separation performance of nylon-66 membranes. However, excessive APTEOS causes the ratio of effective thickness over porosity (Delta x/A(k)) reduces significantly resulting a lower permeability membrane. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 3339-3350, 2011