She died around 7.30 am while undergoing treatment at Gandhi Hospital in Secunderabad, Deputy Commissioner of Police (north zone) B Sumathi said.
The woman worked as a receptionist at an aluminium fabrication unit, police said.
As per preliminary investigation, the man, aged around 28, last evening called her to Lalaguda area, located about 10 kms from here.
After she reached the spot, the man suddenly poured kerosene on her and set her on fire before fleeing, a police official yesterday said.
More From This Section
The woman, who suffered 60 per cent burns, was then shifted to the hospital.
"She passed away this morning. We are now altering the case sections also," Sumathi said.
The police had yesterday registered a case under IPC section 307 (attempt to murder).
A police official earlier said the man was apparently in love with the woman and was harassing her.
However, the woman never told her family members about the man or the harassment, the official said.
The police neither disclosed any details about the man nor confirmed if he was taken into custody.