The Simpson Desert in Australia's southwest Queensland has claimed the life of a 25-year-old man after the four-wheel drive that carried him and his partner bogged down. His partner is still in recovery.

Mauritz "Mo" Pieterse died on Monday while doing a morning routine check of a spring near the Ethabuka Station nature reserve. Colleagues became distressed when Mr Pieterse, along with an unidentified 30-year old co-worker, failed to return back by late afternoon.

A manhunt was organised to look for the two men. Around midnight, Mr Pieterse's body was found dead on a dirt track.

It was later learnt the Toyota Hilux four-wheel-drive that the men used bogged about 16km south of the homestead.

The unidentified companion miraculously survived the dehydration and extreme heat exposure, although was also already near death. He was declared in a stable condition in Mt Isa by Wednesday morning.

"The two people decided to walk and it was very, very hot and one of them has died," police told AAP on Wednesday. Temperatures in Simpson Desert exceeded 40 degrees.

"Another worker from the station came across the other man and he was pretty sick."

Ethabuka Station, located 1600km west of Brisbane and 200km north of Birdsville, covers 215,000 hectares in the north-east corner of the Simpson Desert. It is owned by the conservation group Bush Heritage Australia.

David Whitelaw, the group's spokesman, said the men's vehicle was fitted with a working radio, which left them wondering why Mr Pieterse did not use it, especially after having undergone safety training in Victoria as recently as last week.

''We are obviously looking forward to getting greater clarification as to what occurred and what led to the circumstance where obviously Mo perished due to some heat exhaustion and dehydration,'' Mr Whitelaw said, adding their group has a range of safety systems in place needed for remote operations.

''The police have identified a few key elements as to what's occurred . . . we're keenly interested in what went wrong."