Three of the defendants, an Egyptian and two Thais, were arrested last May ahead of a visit to Cambodia by US Secretary of State Colin Powell, as police announced they had smashed a radical Islamic network.
They will face court along with a Cambodian suspect, 23-year-old Sman Ismael who was arrested in June, and another Egyptian who will be tried in absentia, said Kao Soupha, the lawyer for the first three defendants.
"I am ready to defend my clients during the trial," he said, insisting along with Sman Ismael's lawyer Mach Try that the men had done nothing wrong.
"I strongly hope that my client will receive justice from the court," Mach Try said. "There has been no proof that my client was involved with JI."
All five face up to 20 years in prison if found guilty.
More evidence sought
The case was postponed last year when the presiding judge said more concrete evidence against the defendants was needed before bringing them to trial.
It was further delayed when the original judge, Ham Mengse, removed himself from the case citing conflicts in his schedule.
Judge Ya Sakhorn has been appointed to preside over the trial. He was not available for comment on Thursday.
The three arrested in May are Egyptian Esam Mohamid Khird Ali, 40, and Thai nationals Abdul Azi Haji Chiming, 35, and Muhammad Yalaludin Mading, 41, while the Egyptian still at large is identified as Rousha Yasser, 33.
Front for al-Qaida
Cambodian authorities said they were members of a JI cell that operated out of an Islamic school on the outskirts of Phnom Penh which was allegedly being used as a front to channel al-Qaida money from Saudi Arabia.
JI has been blamed for a series of attacks, including last year's 2002 Bali bombings that killed 202 people and a blast at a luxury hotel in Jakarta that left 12 dead in 2003.
Cambodia's lawlessness and culture of impunity have raised fears that the country could become a haven for terrorists.