Taiwan's High Court has rejected an appeal by former President Chen Shui-bian against his corruption conviction.
But the court in Taipei reduced his sentence from life imprisonment to 20 years, saying the amount embezzled was less than previously ruled.
Chen was convicted in September 2009 of embezzling state funds, committing forgery and money laundering.
He denies the charges and has said he is being punished by the pro-Beijing government for his independence views.
Chief judge Teng Chen-chiu said the court decided to reduce Chen's sentence because it "considered the amount of embezzled public funds smaller than the lower court", but gave no further details.
His original conviction involved the misuse of a total of $15m (£9m) in public funds between 2000 and 2008.
Chen's wife, Wu Shu-chen, who was also jailed over corruption in 2009, had her sentence reduced to 20 years, reports said.
Chen Sung-shan, chief secretary of Chen's office, said the former leader was "very unsatisfied" with the ruling and would appeal again, the AFP news agency reported.
His lawyer, Shi Yi-lin told the Associated Press that Chen believes he should have been acquitted of all charges, but also that he "has a good chance on the next appeal so he was not particularly upset".
Chen's family has returned several million dollars and Chen, who says the alleged bribes were campaign contributions, has apologised for misusing some of the money.
His supporters say the current Taiwanese government - which favours closer relations with China - is persecuting the former president for upsetting Beijing by pushing for formal independence while he was in office.
The BBC's Cindy Sui in Taipei says Taiwan's current President Ma Ying-jeou has made efforts to improve relations with China since he led the Kuomintang (KMT) party into office in 2008.
Taiwan and Beijing have restored direct flights and increased tourism, and Mr Ma is also expected to sign a landmark - though controversial - bilateral free trade agreement with Beijing later this month.
The government has insisted Chen's case is being dealt with according to the law, says our correspondent.
Taiwan has been ruled separately from China since the end of the Chinese civil war in 1949, when the defeated Kuomintang retreated to Taiwan to create a self-governing entity.
But Beijing sees the island as a breakaway province which should be reunified with the mainland, by force if necessary.