The first layered vanadium borophosphate (imidazolium)(3.8)(H3O)(1.2)[(VO)(4)(BO)(2)(PO4)(5)]. 0.3H(2)O (1) has been synthesized hydrothermally and characterized by chemical analysis, infrared and Raman spectroscopy, and thermogravimetric and magnetic measurements. The compound crystallizes in the monoclinic space group C2/c, a = 9.4737 (5) Angstrom, b = 22.1444 (12) Angstrom, c = 17.2192 (13) Angstrom, beta = 105.936 (1)degrees, Z = 4. The structure contains a novel borophosphate secondary building unit, [B2P5O22], in which two BP2O10 trimers are linked by an additional PO4 tetrahedron. These units are connected by V(IV)(2)O-8 dimers and V(IV)O-5 square pyramids to form layers. The space between the layers is filled by disordered imidazolium and hydronium cations and water molecules that form a complex network of hydrogen bonds. A model for the interlayer disorder is proposed.