The victim (aged about 21), a final year student of engineering, and the alleged offender were known to each other, and were having a strained relationship for the last several days.
The alleged offender (30) is a petty businessman and is married, the police said.
According to the woman, the man called her to his shop in Nalgonda, poured kerosene on her and set her afire, the police said.
The woman sustained major burns in the incident, police said, adding that the man is absconding.