Gas-phase standard state formation enthalpies of 63 nitrogen-containing compounds (NCCs) were studied by computational methods. Gaussian-n and complete basis set composite methods were applied. After the calculation of the set of NCCs, the results were analyzed in several ways. All the seven selected methods depicted various precisions in this work. According to the calculations and further data processing, G4 was proven to be appropriate and capable of formation enthalpy calculations on NCCs with a mean absolute deviation of 0.63 kcal/mol. Thus, G4 calculation may help us on choosing experimental values and conducting predictions. Isodesmic reactions using G4 methods are also conducted and further correction was given. The high accuracy of G4 method makes it reliable for calculating gas-phase enthalpies of formations and allows them to serve as a valuable check on the accuracy of reported experimental data. (c) 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012