Bout, a former Soviet air force officer, was arrested in Bangkok in March following a year-long sting operation led by US drug enforcers posing as Colombian Farc rebels.
Thailand's criminal court will decide whether there is enough evidence to send Bout, nicknamed the "Merchant of Death" for his alleged role in supplying weapons to some of the world's bloodiest conflicts, to face US terrorism charges.
US authorities say Bout allegedly sought to sell millions of dollars of weapons to Farc rebels, which the US lists as terrorists.
He is also charged with conspiracy to kill US officers or employees, and conspiracy to acquire and use an anti-aircraft missile.
Bout, who has denied all charges, faces life in prison if convicted by a US court.
US authorities accuse Bout of having been a global gun-runner since the 1990s.
He is accused of having supplied arms to Taliban fighters, Osama bin Laden's al-Qaeda network and Charles Taylor, the former Liberian leader accused of orchestrating militia atrocities during Sierra Leone's 10-year civil war that ended in 2003.