Clingendael trains scores of diplomats each year, but Perlot said working with the Syrians had a different dynamic because of the emotional charge they brought to the table.
The opposition figures tended to start from that ideological standpoint they are in the right, he said, but have to learn to accept that they may have to be flexible with the people they have to deal with.
"That is for them very difficult to accept, because if you think that you have to negotiate with a criminal or if you have to start with Russia who is supporting a criminal that's their words, not mine necessarily how do you shift away from the feeling?" Perlot said.
He said the experience should also help with the group's talks with other opposition groups. Many within Syria's splintered opposition movement feel a deep sense of disillusionment and distrust toward the Syrian National Coalition, who are viewed by many as out-of-touch exiles with inflated egos and non-Syrian allegiances.
In a video posted on Clingendael's website, coalition Secretary General Badr Jamous welcomed the lessons he learned in The Hague.
"We need this help for our negotiations with the regime and even inside Syria," he said. "We now have a lot of problems inside Syria."