Nigeria on 17 October 2014 sealed a deal with the militant group Boko Haram to free the girls.
The Chief of Defence Staff of Nigeria Alex Badeh announced the truce. However, Boko Haram has not made any public statement.
The deal was signed at the close of a three-day security meeting between Nigeria and Cameroon. The arrangements for the release of girls would be finalised at another meeting next week in Chad's capital, Ndjamena.
In May 2014, Boko Haram sparked global outrage by abducting more than 200 schoolgirls. The girls were seized in the north-eastern town of Chibok in Borno state, and their continued captivity has led to criticism of the Nigerian government's efforts to secure their release.
The group has been fighting an insurgency since 2009, with some 2000 civilians reportedly killed in 2014.
In July 2014, Cameroon, Nigeria, Chad and Niger agreed to form a 2800 strong regional force to tackle Boko Haram militants.
About Boko Haram Group
The group promotes a version of Islam which makes it haram, or forbidden, for Muslims to take part in any political or social activity associated with Western society.
It frequently attacks schools and colleges, which it sees as a symbol of Western culture.
Human Rights Watch has reported that 2053 civilian were killed in the first half of 2014, while Amnesty International estimated that 4000 people were killed in violence including Nigerian military operations - in the first seven months of 2014.
When: 17 October 2014
Why: to free the girls