Hydration of an alkene is the acid-catalysed electrophilic addition of water across a carbon–carbon double bond (C=C) to give an alcohol. It matters as a direct way of converting alkenes into alcohols, and it follows Markovnikov's rule. Every step is reversible, so the same catalyst and conditions, run in reverse, bring about dehydration, the elimination of water from an alcohol back to the alkene.

烯烃的水合是在酸催化下,水对碳碳双键(C=C)的亲电加成,生成醇的反应。它之所以重要,是因为它是把烯烃直接转化为醇的途径,并遵循马氏规则。其各步均可逆,因此同样的催化剂和条件反向进行即可实现脱水,即从醇消除水重新生成烯烃。