Used in density gradient centrifugation to separate biological molecules like DNA and viruses based on their density. The high density of caesium chloride solutions allows particles to migrate to their isopycnic points, forming distinct bands that can be collected separately. It is also used in medical applications, particularly in some experimental cancer treatments and cardiac imaging, due to its ability to mimic potassium in cellular uptake processes. Additionally, it serves in the preparation of other caesium compounds and in certain types of radiation detection equipment.