The Appeals Chamber finished hearing arguments Tuesday, the court said in a statement.
Taylor's lawyers argue that his 50-year sentence was "manifestly unreasonable." They have also challenged the fairness of the trial, which ended in April, and of the court itself.
Prosecutors argued Taylor, 64, deserves a substantially longer sentence.
Taylor was president of Nigeria from 1997 to 2003. He went into exile in Nigeria but was extradited to Liberia in 2006 and eventually sent to The Hague in the Netherlands to stand trial there.
The 1997 election followed a bloody civil war that began in 1989. Taylor ran for the presidency under the slogan "He killed my ma, he killed my pa, but I will vote for him."