Production of fly ash zeolites may be an attractive method for the utilization of solid wastes from the energy sector. Different methods of synthesis often yield a variety of zeolite types, thereby affecting the properties of the resulting materials. The attention paid to carbon dioxide emission reduction technologies fully justifies the study of the sorption behaviours of fly ash zeolites synthesized by different methods. This work investigates the sorption properties of fly ash zeolites synthesized with different methods using CO. Sorption capacity and adsorption isotherms were determined following the volumetric method and textural parameters were resolved according to the Dubinin-Astakhov (DA) method. The CO sorption capacity was in the range 0.24-4.16 mmol/g. The relationships between structure and sorption behaviour were studied for each synthesis method. Some strong similarities between commercial zeolites and fly ash zeolites were found. The mechanism for sorption was proved to be physisorption which is fully reversible under selected conditions. The observed trends were used to identify the best sorbent.