Ethylene adsorption was studied by use of DFT/B3LYP with basis set 6-31G(d, p) in Gaussian' 03 software. It was found that ethylene has adsorbed molecularly on all clusters with pi adsorption mode. Relative energy values were calculated to be -50.86 kcal/mol, -20.48 kcal/mol, -32.44 kcal/mol and -39.27 kcal/mol for Ni-13 nanocluster, Ni-10(1 1 1), Ni-13(1 0 0) and Ni10(1 1 0) surface cluster models, respectively. Ethylene adsorption energy is inversely proportional to Ni coordination number when Ni-10(1 1 1), Ni-13(1 0 0) and Ni-10(1 1 0) cluster models and Ni-13 nanocluster are compared with each other. (C) 2010 Elsevier B.V. All rights reserved.