The huge molecular cluster [Fe₃₀Mo₇₂] has been used as a source of catalystnanoparticles in catalytic chemical vapour deposition (CCVD) process ofcarbon nanotubes (CNTs) synthesis. Thermal decomposition of [Fe₃₀Mo₇₂] in air is shown by X-ray diffraction analysis to produce iron molybdate, which isconverted to alloyed Fe-Mo and Fe nanoparticles at elevated temperature andreduction environment. These nanoparticles supported on MgO, catalyse thegrowth of single-walled, double-walled and/or multi-walled CNTs dependingon the active metal loading and ratio of methane and hydrogen in thefeedstock. The structural parameters of the products are studied bytransmission electron microscopy and Raman spectroscopy. The best CNTsamples are tested as field electron emitters.