In this work the insertion reaction of ethylene into the Rh-H bond was studied using different levels of theory. It is shown that the coordination and reaction energies are affected by the correlation functional used. The BP86, B3P86 and PBE functionals provides energetic results in satisfactory agreement with the CCSD(T)//CISD calculation. The MPn calculations give results in complete disagreement with the DFT methods and also with the experimental observations. However, the MP2 and MP3 results are dramatically improved upon the application of the spin-component-scaling procedure. The SCS-MP3 method shows an excellent agreement (< 1 kcal mol(-1)) with the reference CCSD(T)//CISD calculation. (c) 2007 Elsevier B.V. All rights reserved.