Mitochondria are hubs for calcium and redox signaling; they take up and release calcium depending on their metabolic needs and generate superoxide radicals and hydrogen peroxide (H2O2) during ATP production. Moreover, mitochondria play a central role in hydrogen sulfide (H2S) metabolism. At low concentrations, H2O2 and H2S serve as redox signaling molecules, but their overproduction can cause oxidative stress and cell damage. As an important regulator of mitochondrial bioenergetics, calcium transport needs to be precisely coordinated; a task executed by a number of proteins residing in the outer membrane and inner membrane and in the mitochondrial intramembrane space. In mitochondria, calcium controls redox signaling, however, the redox regulation of calcium transporters is less well understood. Here, we summarize the latest findings on mitochondrial calcium- and redox signaling and focus on describing the role of oxidative thiol modifications in the control of the mitochondrial calcium transport machinery.