"The hearing on April 9 will consider the admissibility of the lawsuit," Beatrix Engelmann, a spokeswoman for the Vienna regional court for criminal matters, told AFP.
The lawsuit was first filed in August and is being spearheaded by Max Schrems, a young Austrian law graduate who has been waging a David-against-Goliath battle against Facebook for several years.
Each of the 25,000 plaintiffs — mostly from Europe but also from Asia, Latin America and Australia — is claiming a symbolic 500 euros ($560) from the US-based online social network giant.
The suit claims a "large number" of violations of users' rights including the "illegal" use of their data and Facebook's participation in the US National Security Agency's snooping programme PRISM.
A further 50,000 Facebook users have registered to join the class action at a later stage.
According to Schrems' advocacy group Europe-v-Facebook, Facebook has refuted the claims, but without explaining why, while seeking to delay the case and question its admissibility.
"Facebook claims that it cannot be sued anywhere effectively," the group said.
"We have reviewed all objections from Facebook in great detail and came to the conclusion that they lack any substance. It seems that they are trying to delay the procedure with arguments that at times are bizarre," the group's lawyer Wolfram Proksch said.
Facebook was not immediately available for comment.