John Smith, also known as Frank has not been seen since last Thursday and police are now significantly concerned for his safety.
He was last seen heading towards Stob Garbh, making his way round to Ben Cruachan during the afternoon.
His car has been successfully traced to this area by police, who are asking people to come forward if they have any information.
Inspector Paul Collins of Lochgilphead Police Office said: “Throughout the weekend and continuing today, extensive searches have been carried out by Police Scotland and partner agencies.”
“There is significant concern for Mr Smith’s safety. I would urge anyone who may have been on this route last Thursday or since, to contact police with any information about your route or any observations you may have made, no matter how insignificant you think it is, please do contact us as your information could assist in our search to locate Mr Smith.”
Frank has been described as being 5ft 10 in height, slim build, with grey hair which is thinning on top.
He was last said to be wearing a dark coloured jacket, with grey trousers, a white shirt and a distinctive white sun cap.
He was also in possession of two walking poles.
Police as that anyone who may have seen Mr Smith or who has any information on his whereabouts, contact Police Scotland via 101, quoting incident number 0922 of 7th August, 2021.