Malcolm McAuley, 51, was reported missing by a concerned neigh-bour who had not seen him at his home in Millburn Avenue, Clydebank, for several weeks.
Police say it is possible that he travelled to Oban and they are appealing for the public to get in touch if they have any information on his whereabouts.
Mr McAuley is white, around 5 ft 8in tall, of medium build and with short auburn hair.
He was last seen wearing a burgundy zipper cardigan and faded jeans.
Officers are conti-nuing to search through CCTV footage and are carrying out local inquiries.
Anyone with any information is asked to contact Dumbarton Police office by calling 101.