Hot Dust-Obscured Galaxies (Hot DOGs) are hyperluminous (LIR>1013 Lsun) infrared galaxies with extremely high (up to hundreds of K) dust temperatures. The sources powering both their extremely high luminosities and dust temperatures are thought to be deeply buried and rapidly accreting supermassive black holes (SMBHs). Hot DOGs could therefore represent a key evolutionary phase in which the SMBH growth peaks. X-ray observations can be used to study their obscuration levels and luminosities. I will discuss the X-ray properties of the 20 most-luminous (Lbol>1014 Lsun) known Hot DOGs at z=2-4.6, presented in Vito et al. (2018). We investigated the individual properties of the 3 sources detected with enough counts to perform basic spectral analysis. One of these sources (W0116-0505) is a Compton-thick candidate. We applied a stacking analysis to investigate the average emission of the remaining individually undetected sources. From hardness-ratio analysis, we constrained the average obscuring column density and intrinsic luminosity to be logNH>23.5 and logLx>44, which are consistent with results for individually detected sources. We also investigated the Lx-L6um and Lx-Lbol relations, finding hints that Hot DOGs are typically X-ray weaker than expected, although larger samples of luminous obscured QSOs are needed to derive solid conclusions. I will also compare our results with other samples of red quasars.