They accuse the Vatican and the Belgian Church of negligence by turning a blind eye to sexual abuse, BBC News reports.
The announcement comes after the Belgian Catholic Church said Monday it was willing to pay compensation to victims of abuse by clergy.
About 500 cases of alleged abuse by Catholic clergy in Belgium have been registered since last year.
Lawyers representing at least 70 plaintiffs said a summons would be served calling on Vatican officials and Belgian bishops to appear before a court in Ghent.
The text of the summons is being translated into Italian before being delivered to the Vatican.
One of the plaintiffs, journalist and author Roel Verschueren, said: “We’ve all been living for years with a church which is in denial. Now we’re turning the situation around.”
Fighting to hold back tears, Jeroen Vyncke, 41, told Reuters he wanted “a just compensation (for) missed professional chances and the lack of long-term social relationships.”