Police say a missing 77-year-old man from Harrogate was last seen at Kirkgate Market in Leeds.
CCTV images showed George Bass getting off a bus at Leeds bus station before going to the market on Wednesday afternoon.
He was reported missing by his wife the same day.
North Yorkshire Police are working with the bus company, CCTV operators and retail outlets to try and piece together his movements.
They are also appealing to the public, including Leeds shop workers to contact them if have seen him.
Anyone with information should call police on 101.