The single crystals of the 'tetragonal' C-60 Polymer were prepared by the polymerization of C-60 single crystals under a pressure of 2.5 GPa at 500 degreesC. The X-ray structural analysis resulted in the orthorhombic space group Immm; a = 9.026(2) Angstrom, b = 9.083(2) Angstrom, c = 15.077(3) Angstrom, and Z = 2; R1/wR2 = 0.0731/0.1719 for 654 observed reflections and 74 variables. The crystal structure represents a pseudo-tetragonal packing of translationally identical adjacent two-dimensional (2D) layers formed by the polymerization of C-60 molecules via [2+2] cycloaddition. (C) 2002 Published by Elsevier Science B.V.