Abstract A comparative study of the magnetocaloric effect (MCE) is reported in two different types of chemically synthesized magnetic nanoparticle systems—cobalt ferrite and manganese zinc ferrite with mean size around 5 and 15 nm, respectively. While CoFe2O4 nanoparticles were synthesized using co-precipitation, the Mn0.68Zn0.25Fe2.07O4 (MZFO) nanoparticles were prepared by reverse micelle technique using AOT as surfactant. Our results indicate that the change in entropy with the change in applied magnetic field (dS/dH) is reasonably large for this class of nanoparticles and has a wide distribution over a broad temperature range covering the region above and below the blocking temperature. The maximum entropy change is influenced by the particle size, overall distribution in anisotropy and magnetic moments.