Copper(II) sulfate, also known as copper sulphate, are the inorganic compounds with the chemical formula CuSO₄(H₂O)_x, where x can range from 0 to 5. The pentahydrate (x = 5) is the most common form. The pentahydrate (CuSO₄·5H₂O), the most commonly encountered salt, is bright blue. 

Copper sulfate pentahydrate is used as a fungicide.