Kupekar was under treatment for cancer since the past few months.
He is survived by his wife Sandhya and three daughters.
Born and educated in Kolhapur, Kupekar was a voracious reader with a huge private collection of books and was engaged in the preservation of historical documents and records pertaining to Chhatrapati Shivaji.
He plunged into active politics in 1966 and handled various responsibilities till he was elected speaker of Maharashtra Legislative Assembly between 2004-2009.
The NCP will have a crucial party meeting here Wednesday afternoon to discuss the resignation of deputy chief minister Ajit Pawar and 19 other ministers from the cabinet.
The meeting will be held at 2 p.m. at Vidhan Bhavan building, NCP spokesperson Nawab Malik said here.