A process for removing trace amounts of moisture and/or one or more impurities from contaminated hydride, inert and non-reactive gases, thus decreasing the concentration of the impurities to parts-per-billion (ppb) or parts-per-trillion (ppt) levels. The gas purifier materials of this invention include thermally activated aluminas, said aluminas including organic alumina materials, modified organic alumina materials, and modified inorganic aluminas. The thermally activated alumina materials of this invention are activated by heating the alumina material at a temperature between about 50 C.-1000 C. in an inert or non-inert atmosphere or in a vacuum and maintaining the activated material in the inert or non-inert atmosphere or in a vacuum atmosphere subsequent to said activation but prior to use.