A method for producing nanostructures on a metal oxide substrate includes the following steps: a) forming metal aggregates on the metal oxide substrate; and b) vapor phase growing nanostructures on the metal oxide substrate covered with metal aggregates, the substrate being heated in the presence of one or more precursor gases, and the vapor phase growth of nanostructures being catalyzed by the metal aggregates. The metal aggregate formation stage a) includes an operation for reducing the surface of the metal oxide substrate by reductive plasma treatment, causing droplets of metal aggregates to form on the substrate, the metal aggregate formation stage a) and the nanostructure growth stage b) being carried out in series in a single shared plasma reactor chamber, the nanostructure growth being directly carried out on the droplets of metal aggregates.