The blaze erupted on the second floor of the Lemon Tree Inn in the 1600 block of East Lincoln Avenue around 7:30 p.m.
The suspect's room was the only one damaged, but as many as 30 other hotel residents were forced to evacuate.
Police say 62-year-old Richard Widry had lived in the hotel for two weeks, but had just checked out following an argument with management.
It took a crew of about 35 firefighters about 20 minutes to knock down the fire. Widry's room was blackened.
No injuries were reported.
Thirty to 40 hotel residents were displaced following the blaze.
Anyone with information regarding the incident was urged to call investigators at (714) 765-7900.
CNS contributed to this report.