Luckily, for adjectives and pronouns the vocative form is the same as nominative. What's more, a lot of people rarely use the vocative, using the nominative instead.

Vocative endings for masculine nouns

Masculine nouns
Regular nouns receive the suffix –e
in the vocative case

sin – son → sine
doktor – doctor → doktore
profesor – teacher/professor → profesore
For nouns ending in –k or -c,
the word ending changes to –če

rođak – relative → rođače
čovjek – man → čovječe
stric – uncle (paternal) → striče
ujak – uncle (maternal) → ujače

For nouns ending in –g or –z,
the word ending changes to –že

vrag – devil → vraže
vitez – knight → viteže

For nouns ending in –h or –s,
the word ending changes to –še

duh – ghost → duše

If the word ends in a palatal consonant
(–č, -ć, -đ, -dž, –š, -ž, -nj, -lj, -j), it usually receives the suffix –u in the vocative

muž – husband → mužu
konj – horse → konju
kralj – king → kralju

Vocative endings for feminine nouns

Feminine nouns

For regular feminine nouns (ending in –a)
the word ending changes to –o

žena – woman, wife → ženo
majka – mother → majko
sestra – sister → sestro

For nouns with more than two
syllables ending in -ica, end in -ice.

sestrica – little sister → sestrice
prijateljica – friend (female) → prijateljice

What happens with first names?

First names

Male names commonly receive the suffix –e in the vocative case

Marin → Marine
Krešimir → Krešimire

Names that end in a vowel and foreign names remain unchanged

Luka → Luka
Ivo → Ivo
George → George
James → James

Female names no longer change in the vocative in spoken language

Iva → Iva
Jelena → Jelena
For female names which end in –ica
the word ending changes to –e		 Janica → Janice

A note on writing in the vocative

The name or the noun describing who we’re addressing must always be separated by a comma in Croatian:

Bok, Ivane! - Hello Ivan!
Kako si, Ana? - How are you Ana?
Profesore, sretan rođendan! - Happy birthday professor!

Exercise: Can you put these words into the vocative case?

profesorica – teacher/professor Answer profesorice

polaznik – participant Answer polazniče

Harry! (name) Answer Harry!

gospodin - mister Answer gospodine

gospođa - lady Answer gospođo

vuk - wolf Answer vuče

Bog - God Answer Bože

susjed - neighbor (male) Answer susjede

susjeda - neighbor (female) Answer susjedo