There are five vowels in Serbian language: a, e, i, o, u, which are always very clear and are always pronounced. The consonant r can also be used as a vowel. All vowels including r can be either long or short, but their lenght does not affect their quality. Neither is their pronunciation affected by their position in the word or by the stress of the word.
There are no diphthongs in Serbian.
  1. a
    a. The short a is similar to the first element of the English diphthong au as in "out", and is fully open.
    	brat 	(brother)	
    	park 	(park)
    	kafa 	(coffee)
    	kada 	(when)		
    b. The long a is closest to a as in "father"
    	dan 	(day)
    	grad 	(city)		
    	vrata 	(door)
    	glava 	(head)	
  2. e
    a. The short e is similar to e as in "men", but rather more closed.
    	pesma 	(song)	
    	mesto 	(place)
    	zzena 	(woman)
    	pero 	(pen)		
    b. The long e is more open than in "men".
    	svet 	(people)
    	led 	(ice)		
    	dete 	(child)
    	reka 	(river)	
  3. i
    a. The short i is clear and shorter than in "give". The mouth is rather open, the lips drawn back a little, the tongue approaching the plate.
    	film 	(film)	
    	sir 	(cheese)
    	izlaz 	(exit)
    	zzivot 	(life)		
    b. The long i is prolonged as in "eat".
    	sin 	(son)
    	zid 	(wall)		
    	zima 	(winter)
    	klima 	(climate)	
  4. o
    a. The short o is similar to o as in "not", but the lips are slightly closed and rounded.
    	sport 	(sport)	
    	brod 	(ship)
    	voda 	(water)
    	noga 	(leg)		
    b. The long i is prolonged as in "eat".
    	sto 	(table)
    	brod 	(ship)		
    	torba 	(bag)
    	prozor 	(window)	
  5. u
    a. The short u is similar to u as in "put". The lips are rounded and pushed forward.
    	jutro 	(morning)	
    	uvo 	(ear)
    	ulaz 	(entrance)
    	muzika 	(music)		
    b. The long i is prolonged as in "eat".
    	drug 	(friend)
    	kljucc 	(key)		
    	ruka 	(ruka)
    	luka 	(port)	
  6. r as a vowel
    a. between two consonants:
    	vrt 	(garden)	
    	prst 	(finger)
    	trg 	(square)
    	krv 	(blood)		
    b. The long i is prolonged as in "eat".
    	rdja 	(rust)
    	rdjav 	(bad)