The present invention relates to novel heterocyclic compounds that are useful as phosphodiesterase inhibitors (PDEs) in particular phosphodiesterase type 4 (PDE IV) inhibitors and phosphodiesterase type 10 (PDE 10) inhibitors, processes for their preparation, pharmaceutical compositions containing them and their use in treating allergic and inflammatory diseases as well as for inhibiting the production of Tumor Necrosis Factor (TNF-.alpha.). ##STR00001##