Abstract: The invention relates to a method of producing a composite comprising nanofibres or nanotubes on a porous ?-SiC substrate, said method comprising the following steps: (a) a catalyst for growing nanotubes or nanofibres is incorporated into said porous ?-SiC substrate or into an SiC precursor; (b) carbon nanotubes or nanofibres are grown from a mixture comprising hydrogen and at least one hydrocarbon; and (c) optionally, said carbon nanotubes or nanofibres are converted to SiC nanofibres. This composite may be used as a catalyst or catalyst support.