Four men are on trial in southern China for attempting to illegally sell eight kilogrammes of uranium.
The defendants were arrested in January and are accused of trying to find buyers for two types of uranium that can be used for nuclear weapons.
Investigators are searching for the uranium, which is believed to have been handed out to potential buyers.
The court in Guangzhou said it would not give a verdict in the trial until the uranium had been found.
The uranium is alleged to have been bought from a uranium mine owner in April 2005 for 200,000 yuan ($26,400, £13,220) per kilogramme.
The four are then accused of attempting to find buyers for it - meeting one businessman who eventually turned them into the police.
The China Daily newspaper says the men were trying to sell uranium types U-235 and U-238, which can be used to make nuclear weapons.
Officials said the uranium would not explode in its raw form, but that it posed a health risk to people who came into contact with it.
According to investigators, the four men said they did not know where the uranium was as it had been circulated between a number of possible buyers.
The Tianhe District Court in Guangzhou said a verdict would not be given until the uranium had been found.
The illegal trade of uranium can, in exceptional cases, carry the death sentence, the China Daily reports.