On Tuesday evening, a team of rescue workers was trying to evacuate the body of the climber whose identity remains unknown.
"We are still checking the identity of the victim," the chief of the Temanggung district Search and Rescue office, Welly, said on Tuesday.
He noted that it took a long time for rescue workers, who began to climb the mountain at 8am, to reach the peak.
SAR member Gito Walngadi said: "A total of 20 people climbed the mountain on Monday via the Kledung area in the district."
There was heavy rainfall and clouds shrouded the mountain when they were climbing it, he pointed out.
Later, Gito said, two climbers were found lying on the side of the mountain`s crater on Tuesday morning.
"One of them had died. He was a resident of Kapulogo village, Kapil sub-district, Wonosobo district. The other was in critical condition," he continued.
Gito stated that the victims might have inhaled the poisonous gas coming out of the crater.