A novel two-dimensional organic-inorganic hybrid vanadate complex [{Co-III(phen)(2)}(2)V8O23] has been hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, XPS spectroscopy, TG analysis and single-crystal X-ray diffraction. The single-crystal X-ray diffraction analysis reveals that compound 1 contains an unprecedented neutral 2D framework constructed of 4,10,12-net sheets. To the best of our knowledge, compound 1 represents the first example of 2D layered vanadium oxide complex constructed of 4,10,12-net sheets. Furthermore, the title compound consists of left-handed and right-handed helical chains, which are further interconnected to form the double-helical chains. (C) Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.