Novel liquid-like nanoparticle organic hybrid materials (NOHMs) which possess unique features including negligible vapor pressure and a high degree of tunability were synthesized and their physical and chemical properties as well as CO2 capture capacities were investigated. NOHMs can be classified based on the synthesis methods involving different bonding types, the existence of linkers, and the addition of task-specific functional groups including amines for CO2 capture. As a canopy of polymeric chains was grafted onto the nanoparticle cores, the thermal stability of the resulting NOHMs was improved. In order to isolate the entropy effect during CO2 capture, NOHMs were first prepared using polymers that do not contain functional groups with strong chemical affinity toward CO2. However, it was found that even ether groups on the polymeric canopy contributed toCO2 capture in NOHMs via Lewis acid base interactions, although this effect was insignificant compared to the effect of task-specific functional groups such as amine. In all cases, a higher partial pressure of CO2 was more favorable for CO2 capture, while a higher temperature caused an adverse effect. Multicyclic CO2 capture tests confirmed superior recyclability of NOHMs and NOHMs also showed a higher selectivity toward CO2 over N2O, O2 and N2.