The effect of the particle size reduction on ferromagnetic (FM) phase transition and magnetocaloric properties of the perovskite manganite La0.9Sr0.1MnO3 was studied. Indeed, it has been proven that the maximum of entropy change (-Delta S-M(max)) and the relative cooling power (RCP) are strongly affected by the particle size. The measured entropy change (Delta S-M) was analyzed using Landau theory. The obtained results have been explained in terms of core-shell model. Moreover, H12 (La0.9Sr0.1MnO3 annealed at 1200 degrees C) having large RCP and Delta S-M values could be an interesting cooling material. (C) 2015 Elsevier B.V. All rights reserved.