The direct y-spectrometry method is used to measure more than 350 residual product nuclide yields from 0.1, 0.2, 0.8, and 2.6 GeV proton irradiated (nat)HgO targets. The y-spectrometer resolution is 1.8 keV in 1332 keV y-line. The resultant y-spectra are processed by GENIE2000 code. The y-1ines are identified, and the cross-sections calculated, by the ITEP-designed SIGMA code using the PCNUDAT radioactive database. The 27Al(p,x)22Nareaction is used as monitor. The experimental results are compared with the yields simulated by the I-IETC, LAHET, INUCL, CEM95, CASCADE, and YIELDX codes that simulate hadron-nucleus interactions.