Martin Rhodes, 46, from West Yorkshire has not been seen since around 8.30am on Wednesday.
It is believed he planned to go walking in Kinlochewe, Highlands, and was reported missing when he failed to return to his accommodation later that day.
A search operation was launched and anyone with information that could help the investigation is being urged to come forward.
Police, Torridon and Dundonnell mountain rescue teams, the Search and Rescue Dogs Association and the HM Coastguard helicopter have been searching the area on Friday.
Inspector Jamie Wilson said: "Martin is an experienced hillwalker but it is out of character for him to be out of contact for this length of time.
"We are continuing to urge anyone with information which could help locate him to get in touch.
"Our searches have been focused on the popular Slioch hillwalking route from Kinlochewe but I would ask anyone who believes they might have seen Martin, or has information on where he planned to walk, to let us know.
"With the conditions having turned colder, I would also ask anyone with a shed, outhouse or somewhere that a person could have sought shelter to check them thoroughly.
Anyone with information which could help is asked to contact Police Scotland on 101, quoting incident 4582 of May 1.