Reaction of (PcRu)(2) with dioxygen under a variety of conditions leads in all cases to a solid amorphous oxygen-containing aggregate formulated as HO-[(Pc)RuO](n)-H. Detailed structural information on this material has been obtained by the large-angle X-ray scattering technique(LAXS). It has been established that the aggregate consists of -(Pc)Ru-IV-O- fragments (the best fitting between experimental and calculated data requiring average n = 11), linked together by linear Ru-IV-O-Ru-IV bridges, with Ru(IV) in the center of the planar Pc ring and in-plane Ru-N-Pc and out-of-plane Ru-O bond distances of 1.923 and 1.845 Angstrom, respectively. The Pc rings are cofacially assembled with an inter-ring spacing of 3.69 Angstrom, staggering (35 degrees) and eclipsing of the rings alternating along the stacking direction, Additional information on the structure and electronic state of this ruthenoxane material has been obtained by IR, resonance Raman, EPR, ESCA, and magnetic susceptibility studies. Its stability as a solid and in a solution of H2SO4 has also been examined. The room-temperature electrical conductivity of the solid, sigma(RT), is 1 x 10(-2) Omega(-1) cm(-1). This value is discussed in the light of the reported values for (PcRu)(2) and other similar metalloxane aggregates.