Private Jason Smith, from Hawick, in the Borders, collapsed with blood seeping from his mouth after humid temperatures soared to more than 40 degrees.
The 32-year-old was taken by ambulance to a medical base where he died at Camp Abu Naji, Al Amarah, on August 13, 2003.
"There was blood coming from his mouth, I looked in his airways and I saw blood," said Sergeant Bernard Doolan, a medical technician who was first to treat Pte Smith after he was found at the foot of a staircase.
Sgt Doolan told the inquest into Pte Smith's death that the Reservist's temperature was "very very" high, but he was not sweating - indicating the latter stages of heat-related illness.
"Pte Smith was declining rapidly," said Sgt Doolan. "A corporal turned up with a stretcher, we managed to get him down stairs into the back of an ambulance. We were dabbing him down with water and started to take his clothes off and pouring water all over him."
The inquest at Oxford Coroner's Court was the second to be heard into Pte Smith's death, after an order by the Supreme Court. The initial hearing in November 2006 ruled that the soldier would not have died if the British Army had followed correct procedures.
Pte Smith's mother Catherine then launched a campaign to enable Human Rights laws to be applied to British troops in combat, leading to the Supreme Court ordering another inquest, following judicial review proceedings.
The First Battalion The Scottish Borderers were based at a stadium known as Al Amarah. One of Pte Smith's comrades, Sergeant Joseph Holmes, described it as a "dusty, overheated, hot hellhole."
Sgt Robert Patterson, the company medic at the time of Pte Smith's death, told yesterday how Pte Smith had been to see him to complain of the effect of the heat four days before his death. Pte Smith exhibited a normal pulse rate and temperature.
Sgt Patterson said that when he saw Pte Smith the following day the soldier had told him "it was all good".
Sgt Patterson said that many troops arriving in Iraq had been affected by the heat, and admitted he had been unprepared for the numbers needing treatment at the Eagle Camp in Kuwait.
He said that on subsequent tours, including four deploy-ments to Afghanistan, he had not experienced another casualty due to heat, due to better training and expertise.
The hearing in front of Oxfordshire Deputy Coroner Alison Thompson continues.