Surat Ikramov, the head of Center for Human Rights Initiatives in Tashkent, is monitoring the trial and was at the scene.
"This morning, we and many other people, went to the Tashkent city court where the hearing was due to start," Ikramov said. "After we waited for one hour, a person came out of the building and said because judges were sick the hearing was postponed till 10 a.m. on [30 January]."
Thirty-eight-year-old Khidoyatova has been a coordinator for the "Sunshine Uzbekistan Coalition" since it was formed in April -- one month before the bloody dispersal of a demonstration alienated the Uzbek leadership from many Western governments.
The Sunshine Coalition has been vocal in its criticism of the government since the crackdown in the eastern city of Andijon.
Khidoyatova was arrested in December at Tashkent's international airport as she returned from Moscow. Russian media had suggested Khidoyatova was scathing in her condemnation of Uzbek President Islam Karimov's administration.
She faces money-laundering and tax-evasion charges, among other alleged economic crimes.
Khidoyatova's sister, Nigora, is also a member of the Sunshine Coalition and heads the opposition Ozod Dehqonlar (Free Peasants) party. She has repeatedly said the charges were politically motivated:
"Of course, Nodira's arrest is politically motivated," said Nigora Khidoyatova. "There is no doubt about it."
The coalition, formed in the wake of a revolution that ousted the post-Soviet administration in neighboring Kyrgyzstan, has regularly called for the removal of the Uzbek government.
Fellow Activist To Face Trial, Too
The Sunshine Coalition's chairman, Sanjar Umarov, is an oligarch with business interests in Uzbekistan and the West. Umarov was detained in late October, and faces similar charges in a trial scheduled to begin on 30 January.
Umarov had demanded an independent probe into the Andijon events, echoing calls from the European Union and the United States. In October, the EU introduced an arms embargo against Uzbekistan after the administration summarily dismissed allegations of indiscriminate use of force against the protesters and rejected calls for an independent investigation.
Umarov also wrote a letter to Russian Foreign Minister Sergei Lavrov, calling for stronger ties with Russia and declaring his intention to seek a solution to the current political crisis in Uzbekistan.
Umarov's lawyer, Vitaly Krasilovsky, visited his client in prison and expressed concern about his declining physical and mental health.
Similar fears have arisen over Khidoyatova's well-being, particularly in a country that the international community accuses of "systematic" torture in prisons and detention facilities.
Fears Over Defendants' Safety
The Center for Human Rights Initiatives' Surat Ikramov watched the 25 January proceedings and expressed strong concerns.
"Something happened during the trial when Nodira Khidoyatova was given the floor," Ikramov said. "Khidoyatova asked to hold the trial behind closed doors and refused to have lawyers. In our opinion, Khidoyatova faced pressure and abuse in detention cell, and maybe was given psychotropic substances -- because her behavior was absolutely incomprehensible."
Nigora Khidoyatova said her sister was holding a Bible and looked "strange." She said her sister sounded depressed and humiliated, paying no attention to her 15-year-old daughter, who was sitting next to her.
Khidoyatova, who has two young children, could face up to seven years in prison if convicted.
(RFE/RL's Uzbek Service contributed to this report.)