The porous, structure of nanostructured vinylpyrrolidone-divinylbenzene (VP-DVB)/MCM-41 composite was characterized using N-2 adsorption at 77 K and positronium annihilation lifetime spectroscopy (PALS), atomic force microscopy (AFM) and Raman spectroscopy. Positron annihilation lifetime spectra were measured during outgassing procedure. The voids of differentiated dimensions were detected in the composite material. The number of free volumes and their dimensions depend on the degree of evacuation of volatile components from the samples. (C) 2009 Elsevier Inc. All rights reserved.