A series of poly(vinyl alcohol) (PVA)-based single-layer organic polymeric membranes were prepared via the crosslinking of PVA with different amounts of formaldehyde. Meanwhile, for comparison, both a three-layer organic polymeric membrane and a hybrid composite membrane were also prepared by the layer-upon-layer method. Their thermal stability and tensile properties were investigated to examine the effect of crosslinking on the membrane performances. Thermogravimetric analysis and differential scanning calorimetry thermal analyses showed that the thermal degradation temperature of the single-layer crosslinked membrane C reached up to 325 degrees C. Tensile testing indicated that the three-layer organic polymeric membrane E had excellent tensile strength among these single-layer and three-layer membranes. The swelling properties revealed that the swelling degree value of these membranes decreased with an increase in methanol concentration; this suggests that they were not easily swollen by the methanol solution, which is meaningful for the separation of organic mixtures. Field emission scanning electron microscopy images exhibited that the crosslinking of functional groups impacted their structures and confirmed that their mechanical properties were related to their structures. These findings suggest that the crosslinking of functional groups is an effective method for adjusting the tensile strength of PVA-based organic polymeric membranes and related hybrid composite membranes. (C) 2011 Wiley Periodicals, Inc. J Appl Polym Sci 122: 1350-1357, 2011