The victims have been identified as Sanjulata Malik (40) and her daughter Sujata Malik (15) of Ratanpur village under Dharmasala police station in the district.
Police caught hold of the accused, identified as Gouranga Malik of the same village, who allegedly poured the deadly substance on the duo.
According to sources, the incident took place late last night when the victims were fast asleep in a room and the accused threw acid on them through the window.
While the widow received more than 40 per cent burn, her daughter sustained minor injuries. They were immediately admitted to a community health centre at Dharmasala and later the widow was shifted to the District Headquarters Hospital (DHH) at Jajpur town after her condition deteriorated.
Dispute over property is stated to be reason behind the attack and investigation was on to ascertain the exact cause, police added.