A former British Gurkha soldier, Min Bahadur Sherchan, was hoping to claim the title of the oldest person to climb Everest back from Japan's Yuichiro Miura, who climbed Everest in 2013, aged 80.
Sherchan was the previous title holder of the oldest man to climb the planet's highest peak when he was 76, back in 2008.
Officials at Nepal's tourism office said the 85-year-old died on Saturday afternoon (6 May). It's believed he had a heart attack, according to the Kathmandu Post.
"I am OK and doing very well here to achieve the goal," Sherchan told THT Online by mobile from the base camp on Friday (5 May) morning.
Earlier this year, before returning to Everest, Sherchan spoke to AFP and said he just wanted to prove to himself that he could still make it to the top of the world.
"My aim is not to break anybody's record, this is not a personal competition between individuals. I wish to break my own record," Sherchan said from Kathmandu in February.
The former Gurkha, who had 17 grandchildren had spent months training for his latest bid for the title, which included a morning yoga workout. He said his blood pressure was normal and that he did not suffer from any respiratory problems, according to a Guardian report. As a Sherpa born in the mountains, he did not have any issue with high altitudes or lack of oxygen.
Sherchan's death is the second of the Everest spring climbing season, which runs from late April to the end of May. Swiss climber Ueli Steck died in April after he fell from a steep ridge while training for the ascent.
The Nepal ministry of tourism said a total of five people had died on the Nepali side of Everest during 2016.
Almost 750 people will be making for the summit of Everest, which reaches a height of 8,848m (29,029 ft).