The information on the Osage vowel and consonant inventory, as well as for the Osage standard notation stems from Quintero (2004: 16-42).
Cf. The Osage vowel and consonantal systems.

Osage vowels

The standard Osage notation is as used by Quintero (2004, 2010). Sounds where my notation differs from Osage standard notation are in bold face.

IPA Standard notation My notation Description
a a a
aa aa long a
e e e
ee ee long e
i i i
ii ii long i
o o o
oo oo long o
u u u
uu uu long u
ã ą ã nasal a, often interchangeable with nasal õ
ãː ąą ãã long nasal a
ĩ į ĩ nasal i
ĩː įį ĩĩ long nasal i
õ ǫ õ nasal ɔ or o, often interchangeable with nasal ã
õː ǫǫ õõ long nasal o

An acute accent on the vowel indicates primary syllable stress; e.g. ́ąke  'run', in my notation ̃ãke; kíkǫða  'want from another', in my notation kíkõða. The difference between Quintero's and my notation for vowels is the use of the symbols for nasals, which in my notation uses IPA symbols for the nasals. I am keeping the double symbols for long vowels for usability and practical reasons, as well as to maintain the words aspect for the reader close to Quintero's notation.

Osage Consonants

Quintero considers underlying segments ph, th and kh which according to her never emerge on the surface; they are marked in bold face in the table.

IPA Standard notation My notation Description
b b c
c c c
cʔ cʔ cʔ glottalized
t͡ʃ č č
ch ch ch postaspirated
hc hc hc preaspirated
ht͡ʃ hč preaspirated
ð ð ð
ɣ ɣ ɣ
h h h
k k k
kʔ kʔ kʔ glottalized
hk hk hk preaspirated
l l l
m m m
n n n
p p p
pʔ pʔ pʔ glottalized
hp hp hp preaspirated
 r r r
s s s
ʃ š š
t t t
ht ht ht preaspirated
w w w
x x x
z z z
ʒ ž ž