Herein we report the preparation of polysulfone/polycaprolactone (PS/PCL) blend membranes using a CO2-assisted phase inversion method. Membranes containing from 0 to 50wt.% of PCL were prepared and analysed in terms of morphology, miscibility, hydrophilicity, transport properties and mechanical performance. Membrane porous structures were characterised by scanning electron microscopy (SEM), showing that significant changes in the morphological characteristics were obtained upon the addition of PCL. The water flux measurements confirmed higher porosity and permeability for membranes with higher PCL weight ratio but contact angles indicated that the hydrophobic nature of the surfaces was increased. Differential scanning calorimetry (DSC) and dynamic mechanical analysis (DMA) experiments showed that PCL addition increased the pores non -homogeneity, improved the damping properties of the membranes and decreased the elastic behaviour. (C) 2007 Elsevier B.V. All rights reserved.