The national flag will be flown at half mast as a mark of respect to the departed leader in all government offices, according to an official statement here.
"Considering the spectacular contribution of Kailashpati Mishra in our social life, the Bihar government has declared one day state mourning today," the statement added.
Mishra, veteran BJP leader and former Governor of Gujarat and Rajasthan, died here yesterday after a prolonged illness.
Chief Minister Nitish Kumar who visted Mishra's residence to pay his respect yesterday had announced that he would be cremated with full state honours today.
BJP patriach L K Advani, Leader of Opposition in Lok Sabha Sushma Swaraj, her counterpart in Rajya Sabha Arun Jaitley, Gujarat Chief Minister Narendra Modi and BJP General Secretary Ananth Kumar are scheduled to arrive in Patna late afternoon to pay their condolences to the departed leader who had his roots in Jan Sangh.
Mishra (89) will be cremated on the bank of the Ganga this evening.