Abstract: We report on a new synthesis protocol for functionalization of water-insoluble ferrocene derivative on gold nanoparticles (AuNPs) in aqueous media. 11-mercaptoundecylferrocene (HS-(CH2)11-ferrocene) (FcSH) was successfully conjugated on AuNPs in an aqueous phase with the help of different thiol-alkylated polyethyleneglycol (PEG) ligands. Cyclic voltammetry (CV) was carried out for a range of sets of ferrocene-functionalized Au nanoparticles (FcSH–AuNPs) which showed electrochemical (EC) adsorption due to dithiolated linkage/self-assembly of monolayers (SAMs) on gold electrode surface. Importantly, the redox activity, aqueous solubility and stability of FcSH–AuNPs were noticed to remain unchanged throughout the study.