3,3′-Dihexyloxacarbocyanine Iodide is a cationic, voltage-sensitive, cell-permeable, lipophilic, green fluorescent, carbocyanine dye which is utilized as a membrane potential probe. At a low concentration, the dye will selectively stain the mitochondria of live cells. At high concentrations the dye will stain the endoplasmic reticulum and other internal membranes. 3,3′-Dihexyloxacarbocyanine Iodide is a photosensitizer that photodamages microtubules. It is also utilized as an electron transport inhibitor and may be used as a probe to study multi-drug-resistant cells.