Chemotherapy is the most common cancer treatment, and metallic anticancer compounds have generated increasing amounts of interest since the discovery of cisplatin. More recently, scientists have focused on ruthenium-based compounds as alternatives for platinum compounds, which seem like ideal therapeutic anticancer alternatives to platinum derivatives. The present study aims to assess whether one or more of three Ruthenium-based nanocomposites, namely Ru+Lysine+CTAB (RCTL), Ru+CTAB (RCT), and Ru+Lysine (RL) exhibit pronounced anti-proliferative properties against different cancer cells. Three Ruthenium nanocomposites have been synthesized by standard chemical methods and characterized by Dynamic light scattering (DLS) and Transmission electron microscopy (TEM). The cytotoxic effect of the three composites has been evaluated by MTT in-vitro assay for different human cancer cell lines, namely MCF7, HepG2, A549, and PC3 versus normal human skin cell line (BJ1). The molecular underlying mechanisms of cytotoxicity have been assessed via qRT-PCR for pro-apoptotic makers P53 and Casp-3, and anti-apoptotic marker Bcl-2 as well as flow cytometric analysis of the cell cycle. Among the 3 nanocomposites, RCTL gave the best sensitivity and cytotoxicity especially on HepG2 with IC