Magnetic entropy change of Dy-0.5(Sr1-xCax.)(0.5)MnO3 nanoparticles (0 <= x <= 0.3) was analyzed at low temperatures to investigate the magnetic refrigeration as a promising tool for hydrogen liquefaction. These samples depict interesting values of maximum magnetic entropy change and large relative cooling power, especially for x = 0.3 sample (about 169 J/Kg). It could be a promising candidate for magnetic refrigeration at cryogenic temperatures. Landau theory presents a discord between the experimental magnetic entropy change and the theoretical one. This disagreement is tending to be in accordance as Ca substitution is increasing and also with augmenting the applied magnetic field. (C) 2017 Elsevier B.V. All rights reserved.