Resumen: In the present project polycaprolactone (PCL) with mesoporous silica (MCM 41) as filler based membranes were prepared and characterized. PCL was chosen because it is biocompatible, biodegradable and has an excellent tensile strength. Because of these characteristics PCL has found diverse applications in several fields: packaging, tissue engineering, drug delivery, etc. MCM-41 is a mesoporous material with hexagonal arrangement of uniform mesopores, highly specific surface (up to 1500 m2/g), and adjustable pore diameter (2 10 nm). Composite membranes were prepared by casting and solvent evaporation method. The inorganic loading of the membranes was measured by Thermogravimetric Analysis (TGA) while structure and morphology were analyzed by Fourier Transform Infrared Spectroscopy (FTIR) and Scanning Electron Microscope (SEM). Permeability test were carried out in a home-made experimental plant. The gases used for permeation were oxygen and carbon dioxide. Theoretical and experimental selectivity were compared. Incorporating MCM-41 nanoparticles reduced O2 and CO2 permeation around 20% and 80% respectively, compared to pristine PCL. Also, incorporating these nanoparticles functionalized with EPTES caused a greater decrease in O2 and CO2 permeation, 26% and 90% respectively. For both composite membranes a higher O2/CO2 selectivity was obtained.