The language had five pairs of vowels, long and short, but long o did not have its short analogue, becoming a "schwa" [@]. Also five nasal vowels were used. Consonants included several affricates, and many Indo-European consonants became very dissimilar to those existing in the Proto-language (d > dj, rs > , -f- > --).
The morphological structure combined both new analytic and ancient synthetic forms. Three inflected noun cases, two genders, two numbers, the definite article. Personal pronouns used many suppletive forms (i.e. from different stems). Verbs used -r- in the 3rd person plural (the feature which unified Khwaresmian with Avestan and Sacian); the past tense was formed from the present stem of the verb.
Khwaresmian had one special trait of syntax which cannot be found in any other Iranian language: the wide usage of pronominal and adverbial suffixes which were shaping the verb (e.g. cy-ta-hi-wa-ber - "he came there before him"). The language first used a variety of Aramaic alphabet, then in the 10th century it took up Arabic script, adding several signs to it.