No injuries were reported.
Nassau County police say Alec Sapounas, of Oceanside, was arrested Thursday evening on charges of reckless endangerment and arson.
The fire occurred on September 17 at Phat Daddy's Bar in Oceanside.
Police allege Sapounas threw an accelerant from a container toward the rear door of the bar and ignited it, causing a large fire.
The back door of the bar was open at the time.