Proto-Anatolian is the proto-language from which Anatolian languages emerged. As with all other proto-languages, no attested writings have been found; the language has been reconstructed by applying the comparative method to all the attested Anatolian languages as well as other Indo-European languages.
For the most part, Proto-Anatolian has been reconstructed on the basis of Hittite, the best-attested Anatolian language. However, the usage of Hittite cuneiform writing system limits the enterprise of understanding and reconstructing Anatolian phonology, partly due to the deficiency of the adopted Akkadian cuneiform syllabary to represent Hittite sounds, and partly due to the Hittite scribal practices.
This especially pertains to what appears to be confusion of voiceless and voiced dental stops, where signs -dV- and -tV- are employed interchangeably in different attestations of the same word. Furthermore, in the syllables of the structure VC only the signs with voiceless stops are usually used. Distribution of spellings with single and geminated consonants in the oldest extant monuments indicates that the reflexes of PIE voiceless stops were spelled as double consonants and the reflexes of PIE voiced stops as single consonants. This regularity is the most consistent in the case of dental stops in older texts; later monuments often show irregular variation of this rule.
Common Anatolian preserves PIE vowel system basically intact. Some cite the merger of PIE */o/ and (marginal and sometimes disputed) */a/ as a Common Anatolian innovation, but according to Melchert that merger was secondary shared innovation in Hittite, Palaic and Luvian, but not in Lycian. Concordantly, Common Anatolian had the following short vowel segments: */i/, */u/, */e/, */o/ and */a/.
The status of the opposition between long and short vowels is not 100% clear, but it is known for certain that it does not continue PIE contrast: Hittite spelling varies in a way that makes it very hard to establish which vowels were inherently long and which short. Even with older texts being apparently more conservative and consistent in notation, there are significant variations in vowel length in different forms of the same lexeme. It has been thus suggested by Carruba (1981) that the so-called scriptio plena represents not long vowels, but rather stressed vowels, reflecting the position of free PIE accent. Carruba's interpretation is not universally accepted; according to Melchert, the only function of scriptio plena is to indicate vowel quantity; according to him the Hittite a/ā contrasts inherits diphonemic Proto-Anatolian contrast, */ā/ reflecting PIE */o/, */a/ and */ā/, and Proto-Anatolian */a/ reflecting PIE */a/. According to Melchert, the lengthening of accented short vowels in open syllables cannot be Proto-Anatolian, and neither can lengthening in accented closed syllables.
Proto-Anatolian is the only daughter language of Proto-Indoeuropean to retain the laryngeal consonants. The letter *ḫ represents the laryngeal *h₂. It also probably represents *h₃, but this is not as certain. 
In addition to the laryngeals, Common Anatolian is also the only daughter to preserve the three part velar consonant distinction from Proto-Indoeuropean. The best evidence for this comes from its daughter language Luvian. 
The voiced aspirated stops lost their aspiration over time and merged with the plain voiced stops. The liquids and nasals are inherited intact from Proto-Indoeuropean, and so is the glide *u̯. No native Proto-Anatolian words begin with *r-. One possibly explanation is that this was also true in Proto-Indoeuropean, while another is that it is a feature of languages from the area where Proto-Anatolian's daughter languages are found.
According to Fortson, Proto-Anatolian had two verb conjugations. The first, the mi-conjugation was clearly derived from the familiar Proto-Indoeuropean present tense endings. The second, the ḫi-conjugation appears to be derived from the Proto-Indoeuropean perfect. One explanation for this is that Anatolian turned the perfect into a present tense for a certain group of verbs, while another, newer idea is that the ḫi verbs continue a special class of presents which had a complicated relationship with the Proto-Indoeuropean perfect.
- Luraghi 1998:174
- Lauraghi 1998:174
- Melchert 1993:244
- Lauraghi 1998:192
- Melchert 1994:76
- Fortson 2009:172
- Fortson 2009:172
- Fortson 2009:172
- Fortson 2009: 173
- Silvia Luraghi (1998). "The Anatolian languages". In Edited by Anna Giacalone Ramat and Paul Ramat. The Indo-European Languages. London and New York: Routledge. ISBN 978-0-415-06449-1.
- Craig Melchert (1987). "PIE velars in Luvian". Studies in Memory of Warren Cowgill. pp. 182–204. Retrieved 2008-10-27.
- Craig Melchert (1993). "Historical Phonology of Anatolian". Journal of Indo-European Studies, 21. pp. 237–257. Retrieved 2008-10-27.
- Craig Melchert (1994). Anatolian Historical Phonology. Rodopi. ISBN 978-90-5183-697-4.
- Fortson, Benjamin W. (2009). Indo-European language and culture : an introduction (2. ed. ed.). Oxford: Wiley-Blackwell. pp. 170–199. ISBN 978-1-4051-8896-8.