Closed caged fullerene-like molybdenum disulfide (MoS2) nano-particles were obtained via an arc discharge between a graphite cathode and a molybdenum anode filled with microscopic MoS2 powder submerged in de-ionized water. A statistical study of over 150 polyhedral fullerene-like MoS2 nano-particles in plan view transmission electron microscopy revealed that the majority consisted of 2-3 layers with diameters of 5-15 nm. We show that the nano-particles are formed by seamless folding of MoS2 sheets. A model based on the agglomeration of MoS2 fragments over an extreme temperature gradient around a plasma ball in water is proposed to explain the formation of nano-particles. (C) 2002 Elsevier Science B.V. All rights reserved.