Officers are continuing to investigate the incident which happened on Mavis Drive on just before 10.30pm on Tuesday, April 10.
Police say offenders knocked on the front door of the property, and smashed a panel spraying the man with the substance before he had a chance to open the door.
The man suffered burns to his face, chest, back and arm and was taken to a specialist burns unit for treatment on Tuesday.
Police patrols were stepped-up in the area as forensic crime scene investigators and fire crews combed the house for clues.
Local Councillor, Paul Clark voiced his concern saying he was "horrified" to hear about the incident.
He said: "I know the police are working hard to reduce crime across Chorley and in Coppull.
"People have a right to feel safe in their communities and especially in their own homes."
The news has sent shock waves through the community in Coppull which prides itself on being a safe and family orientated area.
Local business owner, Ari Mohammed, who runs The Turkish Barbers on Spendmore Lane said he was shocked to hear the news.
He said: "I've never heard about anything like this happening in this area before.
"I've been here for years and this is the first time I have heard about anything like this.
"I wish the people involved a fast recovery."
Police investigations into the incident continue.