Masked burglars threw a noxious substance at their victim when he confronted them in his home near Pontefract.
A gang wearing balaclavas broke into the property on Bell Street, Upton, in the early hours of this morning.
When the man, in his 30s, confronted them, they threw the ammonia-based liquid in his face before escaping empty-handed in a black Range Rover.
The man was taken to hospital for treatment for breathing problems.
Detective Inspector Dave Watts, of Wakefield District CID, said: “He remains in hospital at this time in a serious, but not life-threatening condition.
“We are continuing to carry out extensive enquiries into the incident and would like to hear from anyone who witnessed the burglary or who has any information that could assist the investigation.
“We would also like to hear from anyone who saw a black Range Rover driving in the area at the time of the incident.”