The design and optimization of natural gas conditioning with adsorbents requires self-consistent data up to pressures relevant to gathering and transportation pipelines. Adsorption isotherms for methane, carbon dioxide, carbonyl sulfide, and hydrogen sulfide have been measured by a custom-built high-pressure manometric adsorption instrument. These isotherms are measured up to 100 bar on zeolite 13X (significantly above the inflection of isotherm). Furthermore, water adsorption isotherms were measured by an in-house modified continuous-flow thermogravimetric adsorption system. For this work, the zeolite 13X was synthesized and characterized by SEM/EDX, XRD, DLS, and FT-RAMAN. Adsorption isotherms (absolute and excess) were determined for the full range of the adsorptives studied. The manometric system was operated from T = 0 to 50 degrees C and the gravimetric system from T = 25 to 150 degrees C. The experimental data are provided in the Supporting Information; a modified-Toth equation was reported, and adsorption enthalpies were calculated. As expected, zeolite 13X shows much stronger adsorption for water at all pressures, followed by the acid gases (H2S and CO2), COS, and then CH4. We note that CH4 adsorption continues to increase with increasing pressure and approaches that of CO2 and H2S near p = 100 bar due to the higher compressibility of adsorbed CH4.