It has been reported that the molecule dimethyl sulfoxide (DMSO) can be effectively utilized as both a stabilizing ligand and a solvent during cobalt (Co) nanoparticle synthesis. Accordingly, stabilization of the nanostructures is provided by electrostatic contributions from the molecular sulfoxide components. This paper reports the synthesis of Co nanoparticles and nanoclusters (i.e., nanoparticle aggregates) of various sizes in DMSO at 25, 50, and 150 degrees C. This study illustrates that the size of the resulting Co nanoclusters is a direct function of the synthesis temperature. Moreover, these Co nanoclusters are composed of smaller Co nanoparticles that preferentially aggregate at increased temperatures during synthesis, where the largest nanoclusters are constructed at the highest synthesis temperatures. Furthermore, it is demonstrated that the smaller Co nanoparticles that makeup the larger Co nanoclusters can be liberated in solution upon the addition of various cosolvents. .