A detailed electrical investigation of oxidized porous silicon (OPS) has been undertaken, using metal oxide semiconductor capacitors. We demonstrate that the dielectric can provide good electrical isolation under moderate electric fields, exhibiting low leakage current, high resistivity reasonably low interface state density, and fixed charge level. The total density of electron traps in the OPS was found to be of the order 10(12) cm(-2) with the charge centroid lying within the oxidized porous silicon layer, rather than in the underlying bulk thermal oxide or OPS/Si interfaces. The conduction mechanism at higher fields nias found to be rather sensitive to the substrate type and hence the microstructure of the OPS and possible metallic contamination. Conduction limiting mechanisms of the tunneling type (temperature insensitive), Poole-Frenkel thermally activated type, and an anomalous conduction (negative temperature dependence) were observed on several typical wafers. We attribute the low barrier height of 0.9 eV, extracted from the samples exhibiting tunneling conduction, to localized injection arising from interfacial asperities. A dominant donor-like trap with depth of 0.9 eV from the conduction bandedge was found in p-type samples showing Poole-Frenkel conduction. Evidence is presented that stress/strain may play a role in the anomalous conduction seen in n-type samples.