The yellow-orange oxonitridosilicate oxide Ce 4 [Si 4 O 4 N 6 ]O was obtained by the reaction of cerium metal with Si(NH) 2 and SiO 2 in a radiofrequency furnace at 1560 8C. The crystal structure was determined by single-crystal X-ray diffraction (a 1033.67(6) pm, P2 1 3, Z 4, R1 0.0412, wR2 0.0678) and powder neutron diffraction. In the solid there are complex cations [Ce 4 O] 10 that are enveloped by a hyperbolical layer structure [Si 4 O 4 N 6 ] 10À . The layer is built up by corner-sharing SiON 3 tetrahedra of Q 3 type. The oxygen atoms of the SiON 3 tetrahedra are terminally bound to Si, while all nitrogen atoms bridge two neighboring Si centres. The crystallographic differentiation of O and N was unequivocally possible by a careful evaluation of the single-crystal X-ray diffraction data combined with latticeenergy calculations by using the MA-PLE concept (Madelung part of lattice energy). Furthermore the results were confirmed by the chemical analyses. Subsequently, the determined N/O distribution and their crystallographic ordering was proved by neutron powder diffraction. In accordance with the molar ratio Si:(O,N) 2:5 the [Si 4 O 4 N 6 ] 10À network may be classified as a layer silicate. In this specific case a hyperbolically corrugated topology of the layers is observed; this is correlated to periodic nodal surface (PNS) representatives.