[en] Spectroscopical investigations of ⁸⁹Br and ⁹⁰Br have been performed, utilizing the formation of the molecular ion AlBr⁺ in the ion-source of an isotope separator on-line a reactor. Detailed level schemes have been constructed for ⁸⁹Kr and ⁹⁰Kr, and the β-strength function of ⁸⁹Br and ⁹⁰Br below the neutron binding energy is presented. The total decay energy of 89,90Br, as well as of ⁸⁹Kr, have been measured by means of β γ-coincidences, and the population of excited states in ⁸⁹Kr via ⁹⁰Br delayed neutrons has been deduced. (orig.)