The magnetocaloric effect (MCE) and electric-dielectric properties of the Nd-cobaltate perovskitesNd0.6Sr0.4Co1xMnxO3(x = 0, 0.3, 0.7 and 1) were investigated for possible use in magnetic cooling appli-cations. Upon Mn substitution, the magnetic exchange interaction is affected by the (Mn4+/Mn3+) ratio,which in turn impacts several physical properties. The XRD patterns of the synthesized compositesrevealed a single phase with an orthorhombic structure with space group Pbnm (62). The orthorhombiclattice distortion increases linearly with the Mn content, reaching a maximum value (D = 7.377  103)for Nd0.6Sr0.4MnO3. The temperature and frequency dependence of the dielectric permittivity was studiedand analyzed using Maxwell-Wagner interfacial polarization and Koops phenomenological theory. Therapid increase in magnetic susceptibility around the paramagnetic (PM)–ferromagnetic (FM) transitiontemperature TCis greatly affected by Mn substitution. The decrease in susceptibility with increasing tem-perature can be attributed to a charge ordering effect. The PM-FM transition occurs in the temperaturerange of 150–200 K. Moreover, the presence of spontaneous magnetization with second-order phasetransitions is observed from Arrott plot isotherms. The MCE was also investigated by determiningDSMand the relative cooling power (RCP), and the maximum value is found for Nd0.6Sr0.4Co0.3Mn0.7O3.These results compare favorably with those reported for similar materials, indicating our materials asa possible candidate for use in magnetocaloric refrigerators