The article provides a descriptive account of the phonology of Kussummiya spoken in southwest Ethiopia. It is basically a qualitative study in that linguistic data are collected from native speakers by using elicitation technique. The collected data are organized and analyzed categorically. The findings of the study show that Kussummiya has 21 attested consonant phonemes and five short and five long vowel phonemes which is a typical feature of Cushitic vowel system. All consonant phonemes geminate and they occur only in word medial position. Consonant gemination and vowel length are phonemic. Consonant cluster occur in word medial position with a maximum of two non-identical consonants. Some of the phonological processes identified in words or across words are: insertion, deletion, devoicing, spirantisation, assimilation and metathesis.