Discrete single-walled carbon nanotubes (SWCNTs) with uniform diameters of 3.0 and 1.8 nm were synthesized using binary arrays that were composed of monodisperse zirconia nanoparticles with a particle size of 2.0 nm and monodisperse iron oxide nanoparticles with particle sizes of 3.3 and 1.8 nm as catalysts for chemical vapor deposition of methane. The agglomeration of iron oxide nanoparticles during the SWCNT growth was prevented by embedding the active catalyst nanoparticles in an inactive zirconia nanoparticle matrix.