3-deoxy-D-manno-octulosonic acid kinase (, kdkA (gene), Kdo kinase) is an enzyme with systematic name ATP:(KDO)-lipid IVA 3-deoxy-alpha-D-manno-oct-2-ulopyranose 4-phosphotransferase. This enzyme catalyses the following chemical reaction
The enzyme phosphorylates the 4-OH position of KDO in (KDO)-lipid IVA.