ABSTRACT This study describes selected aspects of the phonetic and phonological structure of the G|ui language, a poorly documented endangered Khoe (Central Khoisan) language spoken in Botwana. It conducts instrumental phonetic investigations, namely analyses of palatograms, linguograms, aerodynamic recordings, sound spectrograms, spectra, waveforms, and pitch measurements, in order to provide an objective basis for the detailed description of phonetic features of consonants, vowels, and tones. The description includes phonetic and phonological topics, involving consonants, vowels, and tones, and in addition, it deals with relevant morphological phenomena, such as the compound verb, verbal reduplication and verbal suffixes. This research also explores some theoretical issues, such as the unitary nature of clicks and their accompaniments, the integration of the clicks and non-clicks within a single set of features, the correct interpretation of tonal structure. Two types of historical sound shifts are also dealt with: namely, palatalization which is involved in the nonclick consonant system, and the click replacement which is involved in the click consonant system. In addition to the phonetic and phonological topics, selected aspects of the sociolinguistic profile of this endangered language are also documented.