The orthoborate ion [B(OH)4]⁻ in aqueous solutions between pH 5 and 12 forms stable boric acid esters with catechole and the catecholamines DOPA, α-methyldopa, dopamine, noradrenaline, adrenaline, and adrenalone. The stoichiometries of the esters in solution, their dependence of pH value and concentration were evaluated by 11B NMR spectra and confirmed by Raman investigations in the catechole system. Additionally, Raman spectra and crystal structure investigations on solid crystalline esters confirm these results. The 1:1 esters show in the 11B NMR spectrum a chemical shift δ of around 8.1 ppm, the 2:1 esters of around 13.5 ppm. The Raman spectra of the catechole ester show lines at 744 cm-1, 826 cm-1, and 1011 cm-1 for the 1:1 ester as well as at 798 cm-1 and 840 cm-1 for the 2:1 ester. Besides the 1:1 and 2:1 ester, a 3:1 compound is found as a solid for catechole. Raman spectra of this compound, unstable in aqueous solution, showed a superposition of the 2:1 ester and free catechole. The crystal structure of the triethylammonium salt, which is monoclinic, space group Cc = Cs 4 (No. 9) with a = 925.3(3), b = 1781.1(2), and c = 1444.4(2) pm; β = 94.22(4)°; Ζ = 4; Dc = 1.229 Mg · m-3, shows that two molecules of catechole are esterified with the orthoborate ion in the form of a spiran-like four-coordinated boron atom, while the third molecule of catechole is freely inserted into the crystal. The crystal structure of adrenaloneborate-monohydrate, which is also monoclinic, space group P21/c = C2 h 5 (No. 14) with a = 942.4(4), b = 888.1(3), and c = 1337.8(3) pm; β = 96.86(5)°; Ζ = 4; Dc = 1.452 Mg-m-3, shows two condensed rings, the aromatic ring being condensed through the two phenolic O atoms with the boron atom, so building a dioxaborolane ring. The two OH-groups at the boron atom build Η-bridges with the water molecule. It may be a zwitter ion with a negative boron atom and a positive nitrogen atom.