Thin films of amorphous silicon suboxide (a-SiO(x) with x<2) have been deposited by reactive r.f. magnetron sputtering from a polycrystalline-silicon target in an Ar/O(2) gas mixture. Previously, we have shown that highly oxygenated a-SiO(x) layers are structurally inhomogeneous. In this paper we bring evidences for the deposition pressure influence on the material's physical properties. The layers' composition was investigated by energy dispersive X-ray (EDX) measurements. Fourier transform infra-red (FTIR) spectroscopy and X-ray photoemission spectroscopy (XPS) were used to study the local atomic structure of the deposited layers. The surface morphology was comprehensively characterised by atomic force microscopy (AFM). The electrical characteristics of metal - SiO(x) - metal sandwich samples are also described in this paper focussing on electrical conductivity and layer capacity. Special attention was paid to an empirical relationship between the internal structure and its electrical properties. Both the surface morphology and the electrical properties are influenced by the internal structure that is designed by modifying the deposition parameters. (C) 2008 Elsevier B.V All rights reserved.