Magnetic, specific heat and magnetocaloric studies have been performed on rare earth calcium manganites; Ln0.5Ca0.5MnO3 (Ln=Gd, Dy). The observed isothermal magnetic entropy change is fairly large at low temperature in the manganites family, which is attributed to the magnetic precursor effect of rare-earth ions. For Gd0.5Ca0.5MnO3, the isothermal magnetic entropy change (−ΔS) at 4K, obtained for 7T magnetic field, is as high as 22.8J/kgK. On the other hand, −ΔS is 8.5J/kgK for Dy0.5Ca0.5MnO3. The large value of magnetic entropy change at the cryogenic temperature range for these compounds is interesting from application point of view.