The aromatic polyamine molecule denoted p-EFTP containing three equivalent tertiary amine groups is studied by electrochemistry and UV-vis-near-IR spectroscopy. Cyclic voltammetry and coulometry show a unique, reversible, oxidation wave corresponding to a three-electron process. Near-IR spectroscopy unambiguously reveals the presence of intervalence transitions in the mixed-valence forms of the molecule under study. A novel analysis allows the extraction of comproportionation constants from the dependence of intervalence absorption bands vs average oxidation state. From the corrected spectra of the mixed-valence forms, it is then possible to evaluate the effective electronic couplings of both mixed-valence forms and to compare this with a theoretical estimation.