KH-176 (Sonlicromanol) is a novel, potent small molecule ROS-redox modulator with the potential for the treatment of mitochondrial diseases. KH-176 targets the reactive oxygen species which are important in the pathogenesis of disorders of mitochondrial oxidative phosphorylation. KH-176 effectively reduces increased cellular ROS levels and protects OXPHOS deficient primary cells against redox perturbation by targeting the Thioredoxin/Peroxiredoxin system.