The 43-year-old Austrian was fined 1,500 euros ($1,900) by a lower court for battery after he punched a Greek truck driver in the face during a 2010 altercation that broke out during a traffic jam near Salzburg.
He parachuted from a balloon above the Earth last month, setting a record for the highest skydive and breaking the sound barrier in the process.
But in Austria, the apparent road rage incident has generated less welcome publicity on the ground.
A three-judge appeals court in Salzburg is set to hear the case on Tuesday. "We contend the judge made a mistake here and didn't take into account the self-defense justification," Severin Irsigler, Baumgartner's attorney, said.
"During the quarrel the Greek truck driver launched a kick at Mr. Baumgartner that he was able to parry. It was so intensive that his shoe flew off. In defending himself he pushed the driver away and struck his face while doing so."
The Oesterreich newspaper quoted the driver, whom it identified only as Dimitrios P, as saying he had given Baumgartner only a slight push and had got a fist in the face in return. "He is no hero," the driver said.
Baumgartner will not appear in person on Tuesday, Irsigler said.
($1 = 0.7730 euros)
(Reporting by Michael Shields; Editing by Andrew Osborn)