The present invention relates to novel heterocyclic compounds that are usefulas phosphodiesterase inhibitors (PDEs) in particular phosphodiesterase type4 (PDE IV) inhibitors and phosphodiesterase type 10 (PDE 10) inhibitors, processesfor their preparation, pharmaceutical compositions containing them and theiruse in treating allergic and inflammatory diseases as well as for inhibitingthe production of Tumor Necrosis Factor(TNF-α).