硫酸铜，又称蓝矾，化学式CuSO₄，无水为白色粉末，含水为蓝色粉末，或因不纯而呈淡灰绿色，是可溶性铜盐。硫酸铜常见的形态为其结晶体，一水合硫酸四水合铜(［Cu（H₂O）₄］SO₄·H₂O，五水合硫酸铜），为蓝色固体。其水溶液因水合铜离子的缘故而呈现出蓝色，故在实验室里无水硫酸铜常被用于检验水的存在。在现实生产生活中，硫酸铜常用于炼制精铜，与熟石灰混合可制农药波尔多液。硫酸铜属于重金属盐，有毒，成人致死剂量0.9g/kg。若误食，应立即大量食用或饮用牛奶、鸡蛋清等富含蛋白质食品，或者使用EDTA钙钠盐解毒。

Copper (II) sulfate, also known as cupric sulfate or copper sulphate, is the inorganic compound with the chemical formula CuSO₄.

This salt exists as a series of compounds that differ in their degree of hydration. The anhydrous form is a pale green or gray-white powder, whereas the pentahydrate (CuSO₄·5H₂O), the most commonly encountered salt, is bright blue. Copper (II) sulfate exothermically dissolves in water to give the aquo complex [Cu(H₂O)₆], which has octahedral molecular geometry and is paramagnetic. Other names for copper(II) sulfate are "blue vitriol" and "bluestone".