Electronic structure and optical properties calculations of NiSi2were carried out using the Full-Potential Linearized Augmented Plane Waves (FLAPW) method, within the Density Functional Theory (DFT) with the Local Density Approximation (LDA). Band structure and total and projected density of states (DOS) are calculated as well as the theoretical Electron Energy-Loss (EEL) Spectrum, utilizing experimental lattice parameters. Our theoretical EELS results are in agreement with recent experimental findings, indicating that the main peak corresponds to a plasmon. Additional peaks in our calculations are identified as interband transitions (at 2.67 eV, 4.77 eV and 6.1 eV) associated to transitions between Ni d and Si p states, and low magnitude plasmons (at 1.3 eV and 4.02 eV). © 2010 Elsevier B.V. All rights reserved.