酸碱电子理论，也称广义酸碱理论、路易斯酸碱理论，是1923年美国化学家吉尔伯特·路易斯提出的一种酸碱理论。该理论认为：凡是可以接受外来电子对的分子、基团或离子为酸（路易斯酸）；凡可以提供电子对的分子、基团或离子为碱（路易斯碱）。因为跳脱了限定氢离子与氢氧根的酸碱概念，这种理论包含的酸碱范围很广，但是，它对确定酸碱的相对强弱来说，没有统一的标度，对酸碱的反应方向难以判断。后来，皮尔逊提出的软硬酸碱理论弥补了这种理论的缺陷。

常见的路易斯酸有：

常见的路易斯碱有：

Lewis acid is a chemical species that reacts with a Lewis base to form a Lewis adduct. A Lewis base, then, is any species that donates a pair of electrons to a Lewis acid to form a Lewis adduct. For example, OH and NH₃ are Lewis bases, because they can donate a lone pair of electrons. In the adduct, the Lewis acid and base share an electron pair furnished by the Lewis base. Usually the terms Lewis acid and Lewis base are defined within the context of a specific chemical reaction. For example, in the reaction of Me₃B and NH₃ to give Me₃BNH₃, Me₃B acts as a Lewis acid, and NH₃ acts as a Lewis base. Me₃BNH₃ is the Lewis adduct. The terminology refers to the contributions of Gilbert N. Lewis.