President Viktor Yushchenko fired Piskun last month. The presidential office accused Piskun of dragging out important investigations.
Piskun claims he was dismissed because of a criminal investigation into one of Yushchenko's closest allies and is asking the court to reinstate him.
Speaking to reporters before the court hearing today, Piskun said he hopes the court will make "a judicial, not a political decision."
(Interfax Ukraine/ITAR-TASS)