The case is seen as a landmark because it will be the first time a businessman has been prosecuted for war crimes by a national court.
Frans van Anraat, 62, was not required to enter a plea or make a statement at the pre-trial hearing on Friday. His trial starts in November. He has acknowledged in the past that he sold chemicals to Saddam's government, but said his actions were neither wrong nor illegal.
The chemicals dealer is said to have exported tons of chemicals between 1984 and 1988 that were turned into mustard and nerve gas, some of which was allegedly used in the 1988 attack on the Kurdish town of Halabja where more than 5000 people died.
Prosecutor Fred Teeven said investigators had strong evidence that Van Anraat calmly went ahead with delivering base materials even after the alleged gas attack, the Dutch broadcaster NOS reported.
Several dozen expatriate Iraqi Kurds came to watch the proceedings, some carrying photographs of family members killed in the attacks.
Prosecutors say evidence against Van Anraat includes "official Iraqi documents" - material which may also be used against Saddam when he goes before the Iraqi Special Tribunal on war crimes charges.
Van Anraat fled to Iraq in 1989 to avoid an extradition request by the United States, which wanted to prosecute him for export violations in the same chemicals sale. He returned to the Netherlands after the start of the US-led invasion in 2003, and has been under arrest here since December 2004.