Calcium iodide is an inorganic compound with the chemical formula CaI2. It is a white or yellow solid with strong hygroscopicity that quickly absorbs moisture and carbon dioxide from the air to form hydrogen iodide and calcium carbonate. Calcium iodide can be dissolved in water to produce a colorless solution, and the solution is alkaline.

1. Dehumidifier: Calcium iodide is highly hygroscopic, so it is often used as a desiccant or dehumidifier to control humidity, especially in applications that require a dry environment, such as electronic equipment, packaging, and laboratories.

2. Chemical analysis: In chemical analysis, calcium iodide can be used as a component of starch reagent to detect the presence of starch. When calcium iodide reacts with starch, a blue complex is formed.

3. Photography and printing: Calcium iodide also has applications in the photography and printing industry, where it can be used as a component of photosensitive materials to affect the imaging process.

4. Medical uses: Calcium iodide has applications in certain medical tests and procedures, such as as as part of a contrast medium in cardiac imaging (cardiac CT scan).

5. Agriculture: Calcium iodide can be used as a plant nutritional supplement to provide iodine needed by plants and promote plant growth.

6. Metal smelting: Calcium iodide can be used as an additive in the metal smelting process to extract or refine certain metals.

7. Isotope production of iodine: Calcium iodide can be used to produce radioactive iodine isotopes, which are used in the medical field to treat thyroid diseases and conduct imaging studies.

8. Antifreeze: Calcium iodide is sometimes used as an antifreeze because it lowers the freezing point of the solution.