While bio(organic-inorganic) compatibility and absence of cytotoxicity are crucial to create a successful nanocarrier for applications in biosensing and drug delivery , the study of its stability before commercialization is quite important. In the present work, the stability of gold nanoparticles (AuNPs) functionalized with L-Cysteine (Cys) and Cysteine-Glycine (Cys-Gly) was studied. The AuNPs surface modification with Cys and CysGly was performed to improve their biocompatibility  and, after that, the stability of capped AuNPs was investigated. The synthetized AuNPs using 10 μM of cysteine and 20 μM of Cys demonstrated stability after 1 month of storage, while all other concentration ratios resulted in the formation of chain-like conglomerates. For AuNP capped with CysGly all modifier concentrations led to stable samples within 1 month of storage.