The interaction between the alpha -dicarbonyls 2,3-butanedione, methyl pyruvate, and pyruvic acid and a single nickel atom was studied using the quantum density functional theory-generalized gradient approximation (DFT-GGA) method. With the exception of 2,3-butanedione, the most stable structure is where Ni forms a single bond with the keto carbonyl moiety. The 2,3-butanedione-Ni chelation complex is only 0.3 kcal mol(-1) more stable than the keto-bonded configuration. The dissociation energy of the Ni-keto carbonyl complexes decreases in the order -COCH3 > -COOH > -COOCH3, in keeping with the greater electron-withdrawing ability of the COCH3 substituent. The bonding properties of the different complexes are discussed in terms of charge transfer, electron delocalization, dipole interactions, and stabilizing O . . .H interactions. The calculated data are briefly compared to experimental data for 2,3-butanedione and methyl pyruvate on Ni(111).