Antonio Noble was last seen when Jerome L. Noble, 31, took him in a gray vehicle Sunday at West 37th St. in Ashtabula at 9 p.m., according to authorities.
The boy has brown hair and eyes. He was taken without a shirt or diapers.
The suspect has brown hair and eyes, is 5 feet 11 inches and weighs 170 pounds. He was last seen wearing gray shorts and hat.
Jerome is bipolar with a history of drug and alcohol abuse, according to police.
Anyone with information is asked to call the police.