A process and apparatus for the decontamination of gaseous contaminants (especially oxygen, carbon dioxide and water vapor) from hydride gases (including their lower alkyl analogs) down to <=100 ppb contaminant concentration are described. The critical component is a high surface area metal oxide substrate with reduced metal active sites, which in various physical forms is capable of decontaminating such gases to <=100 ppb, <=50 ppb or <=10 ppb level without being detrimentally affected by the hydride gases. The surface area of the substrate will be >=100 m2/g, and preferably 200-800 m2/g. Oxides of various metals, especially manganese or molybdenum, can be used, and mixtures of integrated oxides, or one type of oxide coated on another, may be used. The substrate is preferably retained in a hydride-gas-resistant container which is installed in a gas supply line, such as to a gas- or vapor-deposition manufacturing unit. The invention provides final decontamination for hydride gas streams intended for gas- or vapor-deposition formation of high purity LED, laser (especially blue laser), electronic, optical or similar products, and can be used in combination with upstream preliminary decontamination process and/or upstream or downstream solid particulate removal units.