The detail magnetic measurements of the polycrystalline La0.2Gd0.5Ba0.3MnO3 (LGBMO) compound have been presented in this manuscript. The compound shows high value of magnetocaloric effect (MCE) (- ΔΔS = 9.1 J/kg-K at 12 K) at low temperature. The experimental results of magnetization and magnetic memory effect confirm the existence of glassy magnetic phase in the compound at the low temperature (T << 35 K). The rejuvenation study further substantiates the presence of glassy phase. This high value of MCE in the LGBMO compound has been addressed by the presence of the glassy phase.