Patnaik was in Tirupati to be present at the convocation ceremony of Rashtriya Sanskrit University.
He was rushed to a hospital after he developed chest pain at night. His body will be brought to Bhubaneswar this afternoon and his last rites will be performed in Puri.
Patnaik was the Governor of Assam between 2009 and 2014. He was Chief Minister of Odisha from 1980 to 1989 and again between 1995 and 1999.