在化学，两性的物质是指既可跟酸反应，又能跟碱反应的物质。例子有氨基酸、蛋白质、水及许多金属如铬、锌、锡、铝、镓、铅和铍。 完整的两性元素有：锡、铍、铬、铋、铝、铅、锌、镓。

这种反应可以用来分开不同的正离子，例如锌和锰。

In chemistry, an amphoteric compound is a molecule or ion that can react both as an acid as well as a base. The word is derived from the Greek word amphoteroi (ἀμφότεροι) meaning "both". Many metals (such as copper, zinc, tin, lead, aluminium, and beryllium) form amphoteric oxides or hydroxides. Amphoterism depends on the oxidation states of the oxide.