...Here we assessed the potential use of a newly discovered Fe2+ reactive probe (SiRhoNox-1) for selective labeling of senescent cells in vitro. For this we have generated and characterized various senescent cell models and subjected them to SiRhoNox-1 labeling. Our results indicate that SiRhoNox-1 selectivity labels live senescent cells and was more specific and faster than current staining such as SA-βGal or a derived fluorescent probe C12FDG. By using SiRhoNox-1, we also showed that intracellular ferrous iron accumulation is secondary to senescence induction and it is not reversed by stress removal. Together these findings suggest that SiRhoNox-1 may serve as a convenient tool to detect senescent cells based on their ferrous iron level.