We have grown "all oxide" transparent p-n junction thin film nanostructure device by using chemical solution deposition and E-beam evaporation onto SiO2 substrate. Combined grazing incidence X-ray diffraction and atomic force microscopy confirm phase pure, mono-disperse 30 nm NiO and 2 at. wt.% Sn doped In2O3 (ITO) nanocrystallites. Better than 70% optical transparency, at a wavelength of 600 nm, is achieved across 160 nm thick p-n junction. The optical band gap across the junction was found to decrease as compared to the intrinsic ITO and NiO. The current-voltage (I-V) characteristics show rectifying nature with dynamic transfer resistance ratio of the order of 10(3) in the forward bias condition. Very small reverse leakage current with appreciable breakdown was observed under the reverse bias condition. The observed optical and electrical properties of oxide transparent diode are attributed to the heteroepitaxial nature and carrier diffusion at the junction interface. (C) 2011 Elsevier B.V. All rights reserved.