The accused, identified as Najeebunnesa (38) is a habitual offender, said Nandlur sub-inspector B V Krishnaiah.
The incident occurred in the evening when Najeebunnesa allegedly entered the house of the victim identified as Krupavathi who is living alone to steal valuables.
Najeebunnesa had apparently carrying acid with her and when the old woman resisted her she flung the corrosive substance on her face, Krishnaiah said.
The victim has been shifted to Chennai for better treatment.