The 79-year-old former president appeared frail and tired and gave brief answers to confirm his identity before the judge. The court allowed Duterte to participate via link due to the long journey to The Hague in the Netherlands.
Even Duterte's daughter, the sitting Vice President of the Philippines Sara Duterte, has traveled to the Netherlands to support her father.
The charges against Rodrigo Duterte concern ordered murders in the Philippines from 2011, when Duterte was mayor of the city of Davao, until 2019 when he had been president for three years.
According to prosecutors, Duterte's campaign, which he himself dubbed the "war on drugs", was part of a "comprehensive and systematic attack directed against the civilian population".
Mainly poor men were targeted, even without evidence of links to narcotics.
The Philippine national police has reported that more than 6,000 people have been killed, while human rights groups put the figure at as many as 30,000.
In a video clip published on social media shortly after Duterte landed in The Hague, he seemed, despite denying wrongdoing, to take responsibility for the actions by saying it was "his job".
The arrest a few days ago in Manila, on the other hand, went chaotically, with a screaming Duterte shouting that "you must kill me to get me to The Hague".
Several steps await before the ICC can initiate a trial. The decision may take several months, or even years.
