A foreigner’s right to Croatian citizenship is laid out in the law on Croatian Citizenship.
Five years continuous residency in Croatia gives you the right to apply for citizenship, as well as if you are married to a Croatian citizen and have a permanent residence permit in Croatia.
The Application has to be submitted to the police together with the documentation needed for residency, proof of the length of your residence in Croatia. This information will be checked by the police.
In the case that a foreigner applies for citizenship on the basis of marriage to a Croatian citizen, it is necessary to provide documents that prove permanent residence, a marriage certificate (not older than 6 months) and the wife’s/husband’s citizenship certificate. The whole procedure is handled by the Ministry of Interior, and a decision is issued by the Minister.