Aqueous solutions of primary and secondary amines such as mono- and diethanolamine are used on a large scale to capture CO2 from industrial streams due to their ability to chemisorb acidic gases like CO2. In regard to corrosion and degradation issues, these amines are generally used in only 20 to 30% concentration in water. Therefore, a major drawback of the solution state CO2 capture is the high heat capacity of these aqueous solutions, making the endothermic regeneration step (stripping) very energy intensive and costly. These amines are also more suitable for the capture of CO2 from gas mixtures, which are practically oxygen free or contain a low concentration of oxygen since these groups of amines tend to degrade over time.(42, 43) To lower the energy cost, amines and polyamines deposited on solid supports have been proposed as an alternative to aqueous solutions. Polymeric amines and polyethylenimines (PEIs) in particular have attracted much attention. The reaction of PEI with CO2 is represented in Scheme 1. The repeating unit of the polymer in this scheme is only a simplified model representation showing the three different types of amines present in PEI. The primary and secondary amino group in PEI react with CO2 to form carbamates. In the presence of water these carbamates can react further to form a bicarbonate species. Following our previous study on PEI impregnated on fumed silica and precipitated silica,(30) we present here our work on the preparation, characterization, and preliminary study of the properties of a silica–organic hybrid adsorbent for CO2 capture from air.