We describe the fabrication of one-dimensional quantum microcavities containing two different layers of molecular J-aggregates. We show that strong coupling can occur between the confined cavity photon mode and the two different molecular exciton modes, leading to the appearance of new 'hybrid' polaritonic modes. Such hybrid states can be described in terms of a superposition of the cavity photon and the two excitonic states. We characterise such cavities as a function of external viewing angle by measuring both the white-light reflectivity and photoluminescence emission following non-resonant optical excitation. We apply a simple model to describe the photoluminescence emission from the cavity by assuming a transfer of population between the different hybrid-polariton modes. We describe the predictions of our model and show that it provides a reasonable qualitative description of the emission. We then use a transfer matrix scattering model to calculate the reflectivity spectra of a cavity, based on an organic semiconductor layer composed of a thin film of J-aggregates deposited onto an inorganic heterostructure containing three InGaP quantum wells. Our results demonstrate that optical hybridisation may be expected between the organic and inorganic excitons in suitably designed structures. © 2004 Elsevier B.V. All rights reserved.