The talks in Havana are aimed at ending five decades of conflict.
As he boarded a plane in the Colombian capital, Bogota, chief government negotiator Humberto de la Calle said the rebels seemed willing to reach "realistic agreements" to give up their weapons and join the political process.
The negotiations will focus initially on the issue of land reform in Colombia, as it was a major reason for the uprising that brought about the establishment of the Farc [Revolutionary Armed Forces of Colombia] in the early 1960s.
Four other points will be discussed: the end of armed conflict; guarantees for the exercise of political opposition and citizen participation; drug trafficking; and the rights of the victims of the conflict.
"This will be a rapid and effective process. A process of months, not years," said Mr De la Calle.
