乙酸盐俗称醋酸盐，是乙酸所成的盐，含有乙酸根离子CH₃COO，即乙酸去掉羧基质子后形成的阴离子。

乙酸根离子的化学式是[C₂H₃O₂]，它是一种羧酸根离子，并且是乙酸的共轭碱。乙酸根离子是从乙酸的去质子化而获得：

CH₃COOH → CH₃COO + H

An acetate /ˈæsᵻteɪt/ is a salt formed by the combination of acetic acid with an alkaline, earthy, or metallic base. "Acetate" also describes the conjugate base or ion (specifically, the negatively charged ion called an anion) typically found in aqueous solution and written with the chemical formula C₂H₃O₂. The neutral molecules formed by the combination of the acetate ion and a positive ion (called a cation) are also commonly called "acetates" (hence, acetate of lead, acetate of aluminum, etc.). The simplest of these is hydrogen acetate (called acetic acid) with corresponding salts, esters, and the polyatomic anion CH₃CO₂, or CH₃COO.