Carbon nanotubes (CNTs) were synthesised in the post flame region of premixed laminar flat H2/air flames using feedstocks containing ethanol and ferrocene. The as-produced nanomaterials were collected downstream of the post-flame region at a fixed height above burner of 230 mm and were characterised by various techniques including Raman spectroscopy, scanning electron microscopy and X-ray diffraction (XRD). A formation window of φ = 1.05–1.20 was identified, and the resulting flame temperatures were found to be the dominant limiting factor for producing CNTs. CNT bundles were formed and the diameter of individual CNTs were observed to be smaller than 5 nm. The formation of CNTs was accompanied by production of highly crystalline nanoparticles of a dimensions between 20 and 100 nm, which were identified as Fe3O4 by XR