The Alvin Police Department is searching for Don Allen, who was last seen in the 15000 block of W Adoue Street at about 12:15 p.m., officials said.
Officials said Allen has a cognitive impairment and believes his disappearance poses an extreme threat to his safety.
Allen is described as a white man, 6 feet 4 inches tall, 175 pounds, with brown eyes. He also has a trach scar on his throat.
He was last wearing a black long-sleeved T-shirt and blue jeans and is using a walker.
Anyone with information on Allen's whereabouts is urged to contact The Alvin Police Department at 281-388-4370.