The 36-year-old man told police someone threw the liquid and lit him on fire at approximately 10:30 p.m. Tuesday in the 4300-block of South Cottage Grove.
Police say no one is in custody.
It was not immediately known if police are seeking one or more than one suspect, according to a lieutenant, who said the victim lives not too far away from where he was burned.
A Wentworth Area police sergeant said the victim was burned on his left side and no one else was hurt.
The Sun-Times Media Wire contributed to this report.