cuso4 solution is a blue copper(II) sulfate salt that easily dissolves in water. The solubility of cuso4 is temperature dependent, meaning that increasing the water temperature allows more and more copper(II) sulfate to be dissolved. In this way, you can control the concentration of your cuso4 solution without having to worry about adding too much copper(II) sulfate. This property of cuso4 makes it useful in a number of chemical experiments, including Fehling's solution and Benedict's solution for testing for reducing sugars. It is also used as a staining agent in chemistry labs, to highlight cell structures such as blood cells and plant tissues. It is soluble in alcohols and glycerin, and when reacting with ammonium hydroxide produces tetraamminecopper(II) sulfate or Schweizer's reagent for testing proteins.

Cu(II) sulfate exists in the form of a hydrate, usually with five molecules of water attached to each copper sulfate molecule. This hydrate, known as copper(II) sulfate pentahydrate or CuSO4*5H2O, is a blue crystal. When anhydrous, it is white or a light gray. Heating anhydrous cuso4 causes it to dehydrate, turning it into the blue aqueous solution that we are interested in working with.

The fungicidal properties of copper(II) sulfate are widely appreciated by farmers and horticulturists for use in the treatment of wood against diseases caused by fungi, such as wood rot and fungus blight. It is also used as an ingredient in fungicides for animal feed, and for the protection of leather products.