A novel two-dimensional nickel trimesate (1,3,5-benzenctficarboxylate), Ni-3(C9O6H3)(2)(H2O)(8), has been obtained by solvothermal route. Its structure is built up from linear trimers of nickel, {Ni3O8(mu(2)-OH2)(2)(H2O)(6)}, connected by trimesate anions. It crystallizes in the triclinic system, space group P-1, with a = 6.6960(3), b = 9.6446(3), c = 10.1114(3) angstrom, alpha = 112.638(1)degrees, beta = 94.008(1)degrees, gamma = 106.476(1)degrees, V = 565.99(4) angstrom(3). Synthesis, X-ray structure determination, thermogravimetric analysis and magnetic properties are presented. (C) 2006 Elsevier Ltd. All rights reserved.