He had undergone open heart surgery at Fortis Escorts Heart Institute after suffering a stroke in Mexico in July past year.
Pachauri was the Chairman of UN's Intergovernmental Panel on Climate Change (IPCC) when it won the Nobel Peace Price in 2007.
He chaired the Intergovernmental Panel on Climate Change panel from 2002 until he resigned in 2015 after an employee at his research firm accused him of sexual harassment.
The IPCC and former U.S. Vice President Al Gore were awarded the 2007 peace prize for their efforts to expand knowledge about man-made climate change and lay the foundations for counteracting it, the Nobel committee said in its award.
Professor Jean-Pascal van Ypersele, the IPCC vice-chairman from 2002 to 2015, said coming from a developing country Pachauri should be credited for drawing the attention, long before others, to the importance of finding synergies between climate policies and sustainable developing agenda. He was admitted to the Escorts Heart Institute in Delhi and had undergone heart surgery at the hospital earlier. "Pachauri had also undergone an open heart surgery but his condition didn't improve", said a source, adding that Pachauri was taken home around 7pm on Thursday, where he breathed his last. Pachauri became chief executive of Teri in 1981 and headed the institute for more than three decades. "The entire TERI family stands with the family of Dr Pachauri in this hour of grief", TERI Director General Ajay Mathur said in the statement. An FIR was registered against Pachauri on February 13, 2015 and he was granted anticipatory bail in the case on March 21, 2015.
But Dr Pachauri was forced to step down from the panel in 2015 over sexual harassment accusations made by a staff member at an Indian environment institute he led. In the statement issued by TERI on Thursday, its Chairman Nitin Desai hailed Pachauri's contribution to global sustainable development as "unparalleled". An alumnus of the Indian Railways Institute of Mechanical and Electrical Engineering in Jamalpur, Bihar, Pachauri served in various positions in the Indian Railways, including at the Diesel Locomotive Works in Varanasi. A court in Delhi framed molestation charges against him in October 2018.