Muhammad Aslam, a mason from Pattoki village, located 70 km from provincial capital Lahore, threw acid on his step-daughters Malaika, 19, and Javeria, 23, while they were asleep last night.
Both victims were brought to Jinnah Hospital in Lahore, where doctors described their condition as critical.
Police said Aslam often quarrelled with his step-daughters on the issue of their marriage. "He wanted to marry them with men of his choice," police official Bashir Ahmed said.
Aslam had allegedly accepted money from a man in his neighbourhood after promising to marry one of the step-daughters to him.
A case was registered against Aslam and police are conducting raids to arrest him.