The Police Directorate said the operation focused on persons arrested late last year in four operations by the German, Austrian and Dutch police forces.
The Croatian police arrested one man in Vukovar, 11 in Zagreb, and several men in Primorje-Gorski Kotar and Dubrovnik-Neretva Counties. All are Croatian citizens.
Purgatory 7 was carried out in 11 counties. The police raided 26 flats, confiscating 39 computers and more than 3,000 CDs and DVDs.
Crime police chief Darko Dundovic said it was likely there would be more suspects.
Croatia included child pornography in the Penal Code in late 2004. Twenty-five persons were arrested in 2006 and 12 in 2005.