Nucleophilicity and CO₂ fixation ability of the ylides of phosphorous, sulfur and nitrogen havebeen assessed using DFT calculations at M06-2X/6-311++G(d,p)//M06-2X/6-31+G(d) level. Nucleophilicityof 54 ylides and their CO₂ adducts have been evaluated using a theoretical nucleophilicity index(N) which shows good linear correlation (R² = 0.87) with Mayr’s experimental nucleophilicity parameter forthe S-ylides. Two key geometrical parameters, condensed Fukui function (fk^-) and Gibbs free energy ofreaction (ΔGr) for the ylide-CO₂ adducts have also been calculated. In absence of steric effect around theylidic C-atom and any other secondary interaction, binding energy of the CO₂-adducts of all the three types ofylides has a good linear correlation with the nucleophilicity. Nucleophilicity of a P-ylide increases whenelectron-donating groups are introduced as substituents on both P and the ylidic C-atom. An electronwithdrawinggroup on the same sites reduces nucleophilicity. Free ylides have higher nucleophilicity thantheir CO₂ adducts.