Maurice Batey, who is 65 and originally from Lamesley in Gateshead, has not been seen since May 2016.
Officers know that in May he flew to Geneva and his family have not heard from him since that date.
Police believe he may be living in Switzerland and are appealing for anyone with any information as to his whereabouts to get in touch.
Maurice is around 1.83m tall, of stocky build and has jet black hair that is swept back.
Anyone with any information is asked to contact Northumbria Police by ringing 101 (if in the UK) or online here.