The non-oxidative thermo catalytic decomposition of methane into COx-free hydrogen and nanocarbon has attracted recent research interest, due to the concern of zero emission of greenhouse gases and the bulk production of value added carbon nanomaterials. In this work, Nickel, Cobalt and Iron based monometallic catalysts supported over sal gel derived silica microflakes were synthesized via a facile wet impregnation route and were successfully used for the direct thermal decomposition of methane into COx free hydrogen and nanocarbon. The active phase of the fresh catalysts was found to be NiO, Co3O4 and Fe2O3. The field emission scanning electron microscopy images clearly indicated the fine dispersion of various agglomerated metal oxide nanostructures on the surface of the sol gel derived silica microflakes. A maximum hydrogen yield of 74% was obtained for the Ni based catalyst, with a slight deactivation with time on stream. The Co and Fe based monometallic catalysts were found to be less active but more stable than the Ni catalyst. Different types of carbon nanomaterials were observed on the surface of the catalysts after methane decomposition. Multi-walled carbon nanotubes, carbon particles with a fruit like morphology and multilayer graphene sheets were obtained over the Ni, Co and Fe catalysts respectively. The Raman and thermo-gravimetric analyses indicated their higher graphitization degree, crystallinity and oxidation stability. (C) 2014 Elsevier B.V. All rights reserved.