A high yield hydrothermal synthesis of the open-framework cobalt borophosphate (C4N2H12)Co[B2P3O12(OH)], has been developed. The compound was characterized by single crystal X-ray diffraction methods, thermogravimetric analysis, vibrational (IR and Raman) spectroscopy and magnetic measurements. In the structure Co(II)O-6 octahedra, BO4 and PO4 tetrahedra form nine-member rings which in turn are linked to form Co-B-P-O layers parallel to the be plane. The layers are. joined together by another set of PO4 tetrahedra and the (piperazinium)(2+) cations occupy the channels running along [100]. The structure is compared with that of (C2N2H10)Co[B2P3O12(OH)]. (C) 2002 Elsevier Science Ltd. All rights reserved.