Solid amine sorbents were prepared using mixtures of linear and branched primary, secondary, and tertiary amines. These amines were immobilized within polystyrene (PS)-, silicon dioxide (SiO2)-, or polymethylmethacrylate (PMMA)-based substrates at various weight ratios. Testing was conducted in various reactor systems, where the reactive water required for the capture of carbon dioxide (CO2) was tracked during the adsorption/desorption cycles by mass spectrometer gas analysis. The water management for these sorbents was quantified and used to assess the technical feasibility of the operating conditions for the capture of CO2 from simulated flue gas streams. In addition, the heats of reaction and performance capture loading capacities of these sorbents were also determined by differential scanning calorimetry (DSC) and thermogravimetric analyses (TGAs), respectively, in both dry and humidified CO2 gas streams. The regenerable solid amine sorbents investigated in this study exhibit acceptable CO2-capture loading capacities of 2.5-3.5 mol of CO2/kg of sorbent by TGA and a laboratory-scale fixed-bed reactor. These sorbents were stable over the adsorption/desorption temperature range of 25-105 degrees C for 10-cyclic tests. According to the DSC analysis, the heat of reaction generated by these sorbents was in the range of 400-600 Btu/lb. CO2, which will require a reactor with heat management capabilities.