坎尼扎罗反应（Cannizzaro反应），也译作康尼查罗反应、康尼扎罗反应、卡尼扎罗反应，是无α活泼氢的醛在强碱作用下发生分子间氧化还原反应，生成一分子羧酸和一分子醇的有机歧化反应。意大利化学家斯坦尼斯劳·坎尼扎罗通过用草木灰处理苯甲醛，得到了苯甲酸和苯甲醇，首先发现了这个反应，反应名称也由此得来。反应的综述参见：。

坎尼扎罗反应中常用的醛有芳香醛（如苯甲醛）和甲醛。对于有活泼氢的醛来说，碱会夺取活泼氢，从而发生羟醛反应，降低坎尼扎罗反应的收率。

分子内的坎尼扎罗反应也是可以发生的，有时产物羟基酸可以进一步失水环化生成内酯。

The Cannizzaro reaction, named after its discoverer Stanislao Cannizzaro, is a chemical reaction that involves the base-induced disproportionation of an aldehyde lacking a hydrogen atom in the alpha position.

Cannizzaro first accomplished this transformation in 1853, when he obtained benzyl alcohol and potassium benzoate from the treatment of benzaldehyde with potash (potassium carbonate). More typically, the reaction would be conducted with sodium or potassium hydroxide: