PAOK goalkeeper Chalkias, at 38 the oldest player at the tournament, said he was bowing out after enjoying his time in the competition.
"This has been one of the best months of my career. Right now I am very emotional and proud -- it was a dream finish for my international career," said Chalkias, who was capped 32 times.
"I am proud and happy to have participated in Greece's effort to reach the quarter-finals," added Chalkias, who started the finals as first choice but played no further part after going off injured in the second group game against Czech Republic.
Striker Liberopoulos, 36, made his senior debut for Greece in 1996 and said the decision to retire was like leaving a family.
Liberopoulos, who failed to make the victorious EURO 2004 squad but regained his place for the finals four years later, said that he had been reluctant to leave the pitch at the end of the Germany game.
He came on as a substitute midway through the second half in Gdansk but failed to add to his 13 international goals. "I feel blessed that I get to close this chapter among a team that are like family to me," the AEK Athens player said.
"It's a big honour for me. At the end of the match, I felt that I didn't want to leave the pitch," added Liberopoulos, who had previously retired from the national side in 2009, only for coach Fernando Santos to persaude him back a year later.