The interest in semiconducting metal oxide nanowires for gas sensing devices is today very high. Besides common materials such as SnO2 or ZnO, also In2O3 has been obtained in this quasi-1D morphology . In the present work In2O3 nanowires have been grown by vapor transport process starting from 6N pure In. For a better knowledge of the fundamental properties and the sensing mechanism of In2O3 nanowires, the obtained samples have been investigated by different techniques, focusing mainly on the optical characterization. Their morphology and structure have been studied by Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM) and X-Ray diffraction. The optical properties have been investigated as well, mainly by means of photo- (PL) and Cathodo-luminescence (CL) both applied in the UV-Visible range. A complex emission spectrum has been revealed and assigned to specific defects thanks to a deep analysis of the bands as functions of temperature (varying from 20 to 300K) and to suitable thermal treatments (in oxygen rich atmosphere at 1000°C). Moreover, the effects of electron beam irradiation have been pointed out by performing CL spectra on a single In2O3 nanowire after different irradiation times. The possible influence of the substrate has been verified by measuring low temperature spectra on In2O3 nanowires grown both on alumina and silicon substrates.