Biopolymers are promising alternatives to synthetic macromolecules for the design of composite materials complying with Green Chemistry principles. In this context, the conditions to associate hydroxypropyl-cellulose and polymethylhydrosiloxane within homogeneous membranes were studied. The stability of these membranes in water and in the presence of a cellulase enzyme were investigated by Thermogravimetric Analysis, Scanning Electron Microscopy and Fourier-Transform Infra-Red Spectroscopy. These investigations reveal that the biopolymer is still accessible to a solubilisation/degradation process without inducing the breaking down of the composite materials, opening the route to the design of novel membranes for environmental applications.