Opposition blogger and journalist Mohammad Abdul-Kader Al-Jassem could still get up to 18 years in prison if convicted of insulting Kuwaiti ruler Emir Sheikh Sabah Al-Ahmad Al-Sabah, one of a number of trials he is facing for his remarks and writings.
His lawyer, Jasser Al-Jidei, said the court on Monday found the opposition blogger innocent of the charge that he had defamed Prime Minister Nasser Al-Mohammad Al-Sabah in a public speech.
The US State Department said in June that it was concerned about Jassem's case and that it had raised the matter with the Kuwaiti government. International human rights groups have also taken up his cause.
Jassem went on hunger strike in May after being detained by the authorities following a complaint against him from the Emir's office, but was forced to stop after several days because of health concerns.
A Kuwaiti court has imposed a ban on news coverage of Jassem's case.
The appeals court also freed Khaled Al-Fadalah, a Kuwaiti politician jailed for slandering the prime minister. The court reduced his three-month prison sentence to 10 days, according to his lawyer Hussain Al-Gharib. He was released late on Monday.
Fadalah, who heads the National Democratic Alliance, a small liberal political movement, was found guilty last month of defaming the prime minister after he accused him of corruption.
The appeals court upheld his conviction, as well as a fine of 150 dinars ($517).
Gharib said his client would most likely appeal Monday's ruling in the hope of an acquittal that would "clear his record."
Kuwait, the world's fourth largest oil exporter, generally allows more press criticism of public officials than other Gulf Arab states, but its ruler is protected from criticism by the constitution.
Many writers have been fined or imprisoned for defamation.
