Applications
Cobalt(II) chloride is used in humidity indicator in weather instruments. In the anhydrous form, it finds use in electroplating of cobalt, in organic chemistry and is a precursor to cobaltocene, (bis(cyclopentadienyl)cobalt(II), which is a good reducing agent. It also serves as a Lewis acid. Cobalt chloride is an indicator for water in desiccants, owing to the reversible hydration/dehydration coupled with distinct color change. Cobalt chloride is useful for producing invisible ink as it turns blue when heated and becomes invisible once it gets cooled. Cobalt(II) chloride catalyzes cross coupling of aryl halides or vinyl halides with aryl grignard reagents in excellent yields.

Solubility
Freely soluble in water and methanol. Soluble in alcohol, acetone, ether, glycerol, and pyridine.

Notes
Hygroscopic. Incompatible with strong oxidizing agents.