氧化物，是负价氧和另外一个化学元素组成的二元化合物，例如氧化铁（Fe₂O₃）或氧化铝（Al₂O₃），通常经由氧化反应产生。氧化物在地球的地壳极度普遍，而在宇宙的固体中也是如此。

氧离子（O）是氢氧根（OH）离子的共轭碱，存在某些氧化物离子晶体中。自由的氧离子具强碱性（pK_b ~ -22），在水溶液中是不稳定的。

氧化物中的氧元素应该呈负氧化态。如果含氧二元化合物中的氧为正氧化态，例如二氟化二氧（O₂F₂）和二氟化氧（OF₂），则它们一般称为氟化物，而非氧化物。

An oxide /ˈɒksaɪd/ is a chemical compound that contains at least one oxygen atom and one other element in its chemical formula. Metal oxides typically contain an anion of oxygen in the oxidation state of −2. Most of the Earth's crust consists of solid oxides, the result of elements being oxidized by the oxygen in air or in water. Hydrocarbon combustion affords the two principal carbon oxides: carbon monoxide and carbon dioxide. Even materials considered pure elements often develop an oxide coating. For example, aluminium foil develops a thin skin of Al₂O₃ (called a passivation layer) that protects the foil from further corrosion. Different oxides of the same element are distinguished by Roman numerals denoting their oxidation number, e.g. iron(II) oxide versus iron(III) oxide.