The Mong Kok Acid Attacks (旺角高空投擲腐蝕性液體傷人案) were a series of acid attacks from 2008 to 2010 where plastic bottles filled with drain cleaner, a corrosive liquid, were thrown onto shoppers on Sai Yeung Choi Street South, Hong Kong, a pedestrian street and popular shopping area. Originally, a reward of HK$100,000 was offered for information about the perpetrator(s), but following the second incident it was raised to HK$300,000, and cameras were planned to be installed in the area. The third incident occurred the very day the cameras were turned on. The fifth incident happened after Hong Kong government announced its new strategies against the incident.

An acid attack, also called acid throwing, vitriol attack, or vitriolage, is a form of violent assault involving the act of throwing acid or a similarly corrosive substance onto the body of another "with the intention to disfigure, maim, torture, or kill". Perpetrators of these attacks throw corrosive liquids at their victims, usually at their faces, burning them, and damaging skin tissue, often exposing and sometimes dissolving the bones. Acid attacks can lead to permanent, partial, or complete blindness.