Microporous silica solids of SiO2 and Ag/SiO2 (a microporous SiO2 substrate containing 5 wt % Ag) are synthesized by the sol-gel method and analyzed through several characterization techniques. The type I shapes of N-2 sorption isotherms at 76 K on these materials indicate large micropore contents as well as important cohesive interactions between adsorbed N-2 molecules, i.e., a gradual cooperative filling process becomes more and more evident as the concentration of adsorbate within the porous structure increases. In addition, negative values of the BET constant are found thus indicating that the adsorption mechanism on these solids can be better described in terms of a volume filling process rather than in terms of a multilayer formation phenomenon. The microporosity existing in these substrata is studied through Sing's alpha(s)-plots. The adsorption capacities of n-alkanes (i.e. n-hexane, n-heptane, n-octane, and n-nonane) on SiO2 and Ag/SiO2 substrata are measured by gas chromatography (GC) at different temperatures. The uptake of every hydrocarbon sorptive, on both SiO2 and Ag/SiO2 substrata, is found to be temperature-dependent. Additionally, the intensities of attractive interactions between hydrocarbon ad molecules and the surfaces of the above solids are evaluated for each adsorbate type from determinations of the isosteric heats of adsorption.