酸性氧化物，即可以与碱反应生成盐和水的氧化物，有时又被称为某酸酐。

如二氧化碳与氢氧化钠反应生成碳酸钠和水：

Acidic oxides are oxides of nonmetals. They can also be termed as inorganic chemicals that react with water forming an acid; or react with a base forming a salt. They are oxides of either nonmetals or of metals in high oxidation states. They are formed when a nonmetal burns. Their chemistry can be systematically understood by taking an oxoacid and removing water from it, until only the oxide is left. The resulting oxide belongs to this group of substances.