Travel documents for minors – Croatia
Other than their own valid travel document, no particular official authorisation is required for minors of any EU country to enter Croatia.
In addition to their own valid travel document (ID card or passport), minors travelling out of Croatia without their parents or other legal guardian(s) must have the authorisation of the parents (or legal guardians) signed and certified by the public notary, diplomatic mission or consular office. This will probably be closely checked to establish whether the minors are leaving their country of their own free will or against the will of their parents/legal guardians.
See thehr for further information.