Judges later withdrew to consider their decision, which opposition figures and defence lawyers, anxious for a quick ruling, expected to be announced only in mid-September. Tymoshenko is serving a seven-year prison sentence.
Tymoshenko has been denied registration as candidate at the 28 October parliamentary elections (see background), on the grounds that her conviction has not been annulled, which in theory the appeal process could do.
The European Union has appointed Pat Cox, former European Parliament president, and Aleksander Kwasniewski, former president of Poland, to monitor Tymoshenko's appeal proceedings on behalf of the European Parliament.
Prosecutors argued that Tymoshenko's guilt had been clearly established at her trial last year. The abuse of office conviction relates to a gas deal which Tymoshenko, 51, brokered with Russia in 2009 when she was prime minister.
The government of President Viktor Yanukovich says the agreement was reckless and saddled the former Soviet republic with an enormous price for strategic supplies of gas which is now taking a toll on the heavily-stressed economy.
Tymoshenko, who is receiving treatment for back trouble in a state-run clinic in the city of Kharkiv and was not present at the appeal hearing, denies betraying the national interest. She says she is the victim of a vendetta by Yanukovich, who narrowly beat her for the presidency in February 2010.
Her prosecution, which has damaged Ukraine's relations with the EU and the United States, will be a major issue in legislative elections on 28 October when Yanukovich's Party of the Regions will seek to retain control of parliament.
'Massive damage on Ukraine'
When the appeal hearing resumed on Tuesday, state prosecutor Oksana Drogobytskaya said Tymoshenko was guilty of a crime which had had serious consequences.
"During the investigation ... the intentional nature of her actions had been established. Everything points to the fact that the actions of Tymoshenko were criminal," she said. "The [gas] contract continues to inflict massive damage on Ukraine."
Tymoshenko's lawyers last week argued in court that negotiating the gas agreement with Russia had been a political act which did not amount to criminal action.
Western governments have called for Tymoshenko's release.
But, with the October election on the horizon, the Yanukovich leadership has shown no signs of freeing Tymoshenko and authorities are instead piling up other charges against her.
In a separate trial, which has been adjourned several times because of her back trouble, she is accused of embezzlement and tax evasion going back to alleged offences when she was in business in the 1990s.
Tymoshenko was a leader of the 2004 Orange Revolution protests that derailed Yanukovich's first bid for the presidency, but failed to produce a strong unified government.
Since Yanukovich defeated her in the election, some of her opposition allies have also faced corruption-related charges.