Multi-walled and single-walled carbon nanotubes (MWNTs and SWNTs) are grown directly on spinel solid solutions (i.e. NiAl2O4, CoAl2O4 and ZnFe2O4) in a methane/air counterflow diffusion flame. Carbon nanotube (CNT) growth occurs through decomposition of flamegenerated carbon precursors (e.g. CO and C2H2) over catalyst nanoparticles (i.e. Ni, Co, and Fe) reduced from the solid oxide. CNT growth characteristics are investigated as functions of spinel composition, local gas-phase temperatures, C-related species concentrations, and sampling positions. CNTs grown from ZnFe2O4 are found to be over 50% in SWNT content. Speciallystructured CNTs such as regularly-coiled, large-bending, and Y-junction nanotubes are observed.