Our group has been working cellulose nanofibrils (OCNF) which form hydrogels in the presence of certain additives. Previously, we have studied the effect of salt, single surfactants and alcohols on cellulose nanofibrils gelation as additives. None of these additives form viscoelastic fluids alone. In order to further extend our control of the rheological behaviour of OCNF hydrogels, we have now begun to explore a mixture of surfactants capable of forming wormlike micelles (WLM). WLM form entangled networks, with properties similar to polymer solutions. We combine these two physical networks in a single system. Here, we would like to use contrast variation studies to evaluate the cross-interactions between these two different networks in order to establish if the rheological behaviour observed is due to synergistic interactions between OCNF and WLM.