水解是一种化工单元过程，是利用水将物质分解形成新的物质的过程。通常是指盐类的水解平衡。

无机物在水中分解通常是双分解过程，属于复分解反应。水分子也被分解成氢离子和氢氧根，和被水解的物质残片结合形成新物质，如：

Cl + H → HCl_(aq)

Hydrolysis (/haɪˈdrɒlᵻsɪs/; fromGreek hydro-, meaning "water",and lysis, meaning "to unbind") usually means the cleavage of chemical bonds by the addition of water. When a carbohydrate is broken into its component sugar molecules by hydrolysis (e.g. sucrose being broken down into glucose and fructose), this is termed saccharification. Generally, hydrolysis or saccharification is a step in the degradation of a substance.