Abstract: Onion-like Fullerenes (OFs) were synthesized by an arc-discharge technique, with different metal nanoparticles as catalysts. The microstructure of the products was characterized and analysed by XRD, SEM, HRTEM and Raman spectroscopy. Results indicated that two kinds of OFs can be prepared in the presence of metal nanoparticle catalysts: 1) individual OFs and 2) OFs encapsulating metal nanoparticles. The structure of OFs with a high degree of graphitization were shown to be similar to graphite. The diameters of OFs were unevenly distributed because of the effect of the size of the metal nanoparticles, which caused Raman spectra showing a frequency shift. A vapour-liquid-solid growth model was used to explain some experimental phenomena during OF formation.