The combustion process of stoichiometric aluminium/copper(II)oxide thermite was experimentally investigated in an optical bomb under inert atmosphere (N-2) and ambient pressure. The reaction zone was monitored with UV/VIS emission spectroscopy and a colour high-speed camera. The emission spectra were analysed by modelling of the background radiation and the characteristic emission of all molecular emitters in the reaction of Al/CuO. Based on this, the particles surface and gas phase temperature, the emissivity and the radiation of energy was determined by a non-linear least squares fit between experimental and modelled spectra. This work presents the first modelling of the diatomic band system of Cu-2 and CuO. The results obtained can help to understand the underlying processes in thermite combustion and the influence of radiation processes in modelling the combustion of thermite mixtures.