The 36-year-old, who has led Australia in one day internationals since 2002 and tests since 2004, has been under pressure after an Ashes defeat to England earlier this year and a quarter-final exit as defending champions at the World Cup.
Cricket Australia has called a news conference for 1pm local time (0200 GMT), promising a "major announcement" involving a "senior Australian cricketer."
Michael Clarke, who stood in for the injured Ponting in the final Ashes test and for the one-day series against England that followed it, is expected to replace his mentor as skipper.