Background Cellulose nanocrystals (CNCs) are highly crystalline rod-shaped nanoparticles, which can be obtained from different cellulose sources through acid hydrolysis. The nanometer size, morphology, facile preparation, and relatively low cost make these nanomaterials a new interesting candidate as precursor of biomass-based carbon nanostructures. Results Cellulose nanocrystals were highly dispersed on the surface and in the internal layers of expanded vermiculite clay (EV) and thermally decomposed to form a carbon coating. SEM/EDS, TEM, IR, Raman, TGA and BET techniques showed the presence of nanostructures formed by films, agglomerates and spherical particles composed of amorphous and graphitic carbon throughout the EV surface. Conclusion The modified EV with carbon nanostructures produced a strongly hydrophobic porous material that can potentially be used to absorb oil in spilling accidents and emerging contaminants in water.(c) 2012 Society of Chemical Industry