The trial of 56 out of 320 suspected Islamic State group militants opened on Monday in the Libya’s western city of Misrata.
The militants were captured after the 2016 fall of the city of Sirte.
The 56 suspects appeared in court but the trial has been adjourned to September 25.
The Islamic State group captured the central city of Sirte in 2015, setting up a stronghold before being driven out the following year by forces loyal to the Tripoli-based Government of National Unity in power at the time.
The suspected jihadists face charges of “joining a terrorist group” and killing members of the GNA forces.
The suspects appeared in the dock clad in blue prison overalls, some with their faces covered, in the crowded courtroom where dozens of the families had gathered.
The 320 suspects facing trial are made up of Syrians, Tunisians, Sudanese and Libyan nationals.
Libya was plunged into over a decade of chaos and lawlessness following the 2011 NATO-backed uprising that led to the removal and killing of longtime dictator Moamer Kadhafi.
Dozens of militias and jihadist groups took advantage of the power vacuum, with Islamic State setting up base in Sirte and the eastern town of Derna before being driven out with the help of US-led air strikes.