氯化亚钴，常称氯化钴、二氯化钴或氯化钴（Ⅱ），化学式为CoCl₂；无水的氯化亚钴蓝色，水合物众多，常见者为红紫色六水物CoCl₂·6H₂O；无水物具吸湿性，水合物具潮解性。

固态六水物中，四个水分子是配位水，两个水分子是结晶水，即[CoCl₂(H₂O)₄]·2H₂O。有水物溶于水和乙醇。

在欧盟的「关于化学品注册、评估、许可和限制法案」（REACH）中，已将氯化亚钴列为高度关注物质(SVHC)。

Cobalt(II) chloride is an inorganic compound of cobalt and chlorine, with the formula CoCl₂. It is usually supplied as the hexahydrate CoCl₂•6H₂O, which is one of the most commonly used cobalt compounds in the lab.

The hexahydrate is deep purple in color, whereas the anhydrous form is sky blue. A blend would be mauve. Because of the ease of the hydration/dehydration reaction, and the resulting color change, cobalt chloride is used as an indicator for water in desiccants.