We report a one of a kind study to develop Europium doped Tantalum oxide nanoparticles for XEOL imaging. X-ray excited optical luminescence (XEOL) is an emerging alternative to in-vivo optical imaging to visualize deep tissues. Therefore, a proper selection of host material is essential to generate high luminescent XEOL probes to acquire molecular information about diseases. Herein, Tantalum oxide nanoparticles (TaOx NPs), a well-known biocompatible CT contrast agent, is used as the host material. In this article, we present the experimental investigation of X% of Europium doped into TaOx nanoparticles (Eu: TaOx NPs) as a potential contrast for XEOL imaging. XEOL measured with TaOx and X% Eu: TaOx NPs showed blue and reddish-orange luminescence when exposed to X-rays. By changing the X-ray voltages between 50 and 200 keV, the intensity of reddish-orange luminescence of X% Eu: TaOx NPs increases gradually. Based on the results, we propose that the enhanced reddish-orange luminescence from Eu: TaOx NPs is due to the energy transfer from host material and direct radiative decay from luminescent centre.