BoB currently holds 98.57 per cent of the total equity share capital of NBL.
Details about the process of transaction are given in the PIM, which will be published on Wednesday for inviting EOI from bidders, it said.
The Mumbai-based BoB had taken over Nainital Bank in 1973 on the directions of the Reserve Bank of India (RBI).
Uttarakhand-based Nainital Bank has about 150 branches across Uttarakhand, Uttar Pradesh, Delhi, Haryana and Rajasthan.