The hostages set for release are Consuelo Gonzalez de Perdomo, 57, a former legislator; Clara Rojas, 44; and Emmanuel, three years of age, the son Rojas bore to a Farc fighter in captivity.
Clash with Uribe
Chavez had been told last month by Alvaro Uribe, the Colombian president, to stay out of hostage negotiations with Farc, however he continued communication with the group.
"I'm dying to be with her and I thank her infinitely for having had the bravery to survive"
Maria Fernanda Perdomo, hostage Consuelo Gonzalez's daughter
Rojas was the presidential campaign manager of Ingrid Betancourt, a French-Colombian former presidential candidate in Colombia who was abducted with Rojas and remains in captivity despite a high profile campaign for her release.
The women are among 45 hostages, including three Americans, whom the rebels want to exchange for about 500 Farc members held by the Colombian government.
However, the two sides have not agreed on conditions for that swap.
"We have firm hope that this will be the first step in a long process, aimed first at resolving the hostage crisis and secondly at finding a peaceful solution to the conflict," Marco Aurelio Garcia, one of the Brazilian special envoys, told Colombian radio.
"I am happy and eager to see her," Consuelo Gonzalez's daughter, Maria Fernanda Perdomo, was quoted by AFP as saying.
"I want to tell her that I adore her, that I'm dying to be with her and I thank her infinitely for having had the bravery to survive these six years and three months in captivity."