Ocean deoxygenation is one of the big impacts of climate change. Decreasing oxygen levels will greatly impact the ocean intermediate depths (200-1500m) and especially oxygen-deficient zones (ODZs). In order to better understand the processes that control ocean oxygenation, we need long-term records, which can only be obtained from geological archives such as sediments and cold-water corals. Chromium and Cr isotopes are sensitive to ocean oxygenation levels, particularly near ODZs. CoralOx is an exploratory project of the MIT-Portugal Program aiming to investigate the use of cold-water coral Cr concentration and isotope ratio as a proxy of paleoredox state of intermediate-depth waters.