This article investigates the treatment of oronasal vowel /ↄ̃/ of the prenominal adjective bon (/bↄ̃/) in liaison, as produced by 19 speakers of Northern Metropolitan French. The oronasal vowel of this word has traditionally been identified as a denasalized vowel in liaison, which, when paired with the liaison consonant [n], is typically understood to be produced identically to the feminine form of the adjective bonne (/bↄn/). To verify this supposition, the adjective pair bon/bonne is produced in various contexts and word sequences by each speaker in a series of reading tasks. Six acoustic measures (i.e., A1−P0, A3−P0, center of gravity, F1 bandwidth, F2 and vowel duration) are taken for each token and the resulting data are analysed in a series of regression models. A brief acoustic description is given for the vowel /ↄ̃/ both in and out of liaison, and comparison is made between bon in liaison and the feminine bonne in prevocalic position (e.g., bon ami vs. bonne amie). Analyses indicate that 15 of the 19 speakers seem to produce bon in liaison distinctly from non-liaison bon, but not distinctly from pre-vocalic bonne, which may support suppletive analyses of adjectives in liaison.