We investigate the excitation of electrostatic wakefields in metallic nanostructures (nanowires) due to the propagation of a short electron pulse. For that purpose, a dispersive (nonlocal) dielectric response of the system is considered, accounting for both the finiteness of the system and the quantum (Bohm) difraction of the conduction electron band, generalizing the results obtained previously in the literature [Phys. Rev. Lett. 103, 097403 (2009)]. We discuss on the stability conditions of wakefields and show that the underling mechanism can be useful to investigate new sources of radiation in the extreme-ultra-violet (XUV) range.Experimental techniques [1] have been developed for the fabrication of metallic nanostructures (nanowires) of the order of 10 nm or less, recently receiving a considerable attention of the scientific community. Nanowires, compared to other low-dimensional systems, have two conned directions, still leaving one unconned direction for electrical conduction. Due to their unique density of states, such systems are expected to exhibit significantly different optical, electrical, and magnetic properties from their bulk 3D crystalline counterparts, specially in the limit of small diameters. Even if the number of electrons involved in the relevant features is high, and therefore a continuum description is expected to be adequate, the current models still lack of completeness. One of the most striking cases is related with the dielectric response. It was experimentally shown that anomalous absorption can occur in thin metal films [2] due to the excitation of plasmons [3]. Liu et al. [4] have recently approached this problem for arbitrarily shaped nanostructures, though neglecting the wavenumber dependence in their model. Recently, McMahon et al [5] have introduced the effects of the nonlocal response by adding dispersion terms (proportional to the wavevector k) in the Drude dielectric function of the bulk (conduction) electrons, as described bywhere ∞ (≈ 1) is the value for ω → ∞, ω p and v F stand for the plasma frequency and the electron Fermi velocity, respectively, and γ represents the electron collision frequency. However, it is well known that further quantum mechanical effects [6] are associated with electrons at nanoscales, playing a significant role in the dispersion of collective modes and instabilities, and therefore are expected to play an important role in nanowires, as well. In particular, such quantum effects become important when the thermal wavelength is comparable to the typical dimensions of the system. In this Letter, we extend the dispersive Drude model in order to cast these quantum corrections and derive a nonlocal dielectric constant for quasi one-dimensional nanostructures (nanowires). More specifically, we take into account the effects of i) the finiteness of the system along the transverse direction and ii) the quantum diffraction (Bohm potential) due to a gradient of the electronic density. We then apply our result to investigate the excitation of wakefields due to...