AbstractTransition metals offer many possibilities in developing potent chemotherapeutic agents. They are endowed with a variety of oxidation states, allowing for the selection of their coordination numbers and geometries via the choice of proper ligands, leading to the tuning of their final biological properties. We report here on the synthesis, physico‐chemical characterization, and solution behavior of two gold(III) pyrrolidinedithiocarbamates (PDT), namely [AuIIIBr2(PDT)] and [AuIIICl2(PDT)]. We found that the bromide derivative was more effective than the chloride one in inducing cell death for several cancer cell lines. [AuIIIBr2(PDT)] elicited oxidative stress with effects on the permeability transition pore, a mitochondrial channel whose opening leads to cell death. More efficient antineoplastic strategies are required for the widespread burden that is cancer. In line with this, our results indicate that [AuIIIBr2(PDT)] is a promising antineoplastic agent that targets cellular components with crucial functions for the survival of tumor cells.