All-electron CCSD(T), QCISD(T) and MP4(SDQ) calculations including relativistic effects via the use of the IORAmm Hamiltonian have been performed for NCO. The optimized molecular geometry is in nice agreement with the recently obtained experimental data. The Pd-CO bond dissociation energy is estimated to be 38.8 kcal/mol. The vibrational spectrum of PdCO is calculated and a reassessment of the experimental datum for the frequency of bending mode is suggested. (C) 2003 Elsevier Science B.V. All rights reserved.