Over the recent years, several Re(i) organometallic compounds have been shown to be toxic to various cancer cell lines. However, these compounds lacked sufficient selectivity towards cancer tissues to be used as novel chemotherapeutic agents. In this study, we probe the potential of two known N,N-bis(quinolinoyl) Re(i) tricarbonyl complex derivatives, namely Re(i) tricarbonyl [N,N-bis(quinolin-2-ylmethyl)amino]-4-butane-1-amine () and Re(i) tricarbonyl [N,N-bis(quinolin-2-ylmethyl)amino]-5-valeric acid (), as photodynamic therapy (PDT) photosensitizers. and proved to be excellent singlet oxygen generators in a lipophilic environment with quantum yields of about 75%. Furthermore, we envisaged to improve the selectivity of via conjugation to two types of peptides, namely a nuclear localization signal (NLS) and a derivative of the neuropeptide bombesin, to form and , respectively. Fluorescent microscopy on cervical cancer cells (HeLa) showed that the conjugation of to significantly enhanced the compound's accumulation into the cell nucleus and more specifically into its nucleoli. Importantly, in view of PDT applications, the cytotoxicity of the Re complexes and their bioconjugates increased significantly upon light irradiation. In particular, was found to be at least 20-fold more toxic after light irradiation. DNA photo-cleavage studies demonstrated that all compounds damaged DNA via singlet oxygen and, to a minor extent, superoxide production.