A series of ternary alloys of general formula SmNi5-xGax (x = 0.25, 0.5, 1.5, 2, 2.5) was prepared by melting mixtures of Sm, Ni and Ga in arc furnace under argon. From X-ray powder diffraction lattice parameters are determined and it is found that hexagonal structure of P6/mmm space group is retained for all considered values of x. Hydrogen absorption ability and thermodynamic quantities of the systems are determined by pressure-composition desorption isotherms. The obtained properties are compared with those of previously reported SmNi5 and SmNi4Ga. DFT calculations were performed for selected members of the system and the results are discussed with regard to experiment. Copyright (C) 2013, Hydrogen Energy Publications, LLC. Published by Elsevier Ltd. All rights reserved.