The woman, aged around 23 years, suffered injuries on her back.
A man threw acid on a married woman in Jeedimetla area in Hyderabad on Friday night, police said.
"The woman reportedly had extra-marital affair and a person known to her threw acid on her when she was walking down a road," assistant commissioner of police (Balanagar Division) N Narasimha Reddy said.
The woman, aged around 23 years, suffered injuries on her back. Some locals immediately took her to a hospital while the man who threw acid fled. Further probe is on, the police officer said.