Metal nanoclusters (1 – 100 nm) are of significance because they exhibit unique physico-chemical properties, very different from those in the bulk. They are used as building blocks for hierarchical materials. These materials can be achieved if the properties of the nanoclusters can be manipulated on all scales (molecular, micro and meso) to incorporate desired characteristics for applications in varied fields ranging from opti-electronic devices, magnetic storage devices, catalysts to medical implants and drug delivery. Wet chemical synthesis is gaining popularity because it provides the flexibility to control nanocluster properties like size, shape and morphology by manipulating the stabilizer parameters like molecular weight, functional groups and concentration. We are interested in understanding the self-assembly process for bulk-synthesis of nanoclusters. In literature, considerable amount of work has been done on how these parameters influence nanocluster properties – however, the stabilization mechanism is not yet fully understood. The processes occurring simultaneously in the system are decomposition, nucleation, growth & aggregation, stabilization and breakage / fragmentation. To get a better understanding of this mechanism we have attempted for the first time, to the best of authors' knowledge, to capture the nucleation and growth pattern using extensive transmission electron microscopy and, more importantly, study how polymers and surfactants influence these. The study is done for different chain-lengths and different stabilizer systems (polymers and surfactants). This will also give us insights around the differences in roles of polymers and surfactants in influencing nano-cluster formation. The model system chosen for this purpose was the thermal decomposition of an organo-metallic precursor, octa-carbonyl di-cobalt in an inert atmosphere in the presence of polystyrene/AOT as stabilizer, both dissolved in a common solvent, toluene. The octa-carbonyl di-cobalt decomposes to give highly active nascent cobalt atoms. FTIR was used to monitor the progress of the reaction. Eight samples were taken out in a 24-hour period (including t=0 and t=24), stored in vials and quenched with liquid nitrogen. These, were then analyzed by TEM. These micrographs captured the size and shape of nanoclusters spanning over the growth period. Interesting observations were made which helped us conclude that polymers are definitely involved in the nucleation and growth process of nanoclusters in a complex manner. Chain length plays a role in the rate at which nanocluster size decreases. Concentration of both polymer and surfactant has an impact on the formation mechanism.