  We have investigated magnetocaloric effect in double perovskite Gd2NiMnO6
(GNMO) and Gd2CoMnO6 (GCMO) samples by magnetic and heat capacity measurements.
Ferromagnetic ordering is observed at ~130 K (~112 K) in GNMO (GCMO), while the
Gd exchange interactions seem to dominate for T < 20 K. In GCMO, below 50 K, an
antiferromagnetic behaviour due to 3d-4f exchnage interaction is observed. A
maximum entropy (-{\Delta}SM) and adiabatic temperature change of ~35.5 J Kg-1
K-1 (~24 J Kg-1 K-1) and 10.5 K (6.5 K) is observed in GNMO (GCMO) for a
magnetic field change of 7 T at low temperatures. Absence of magnetic and
thermal hysteresis and their insulating nature make them promising for low
temperature magnetic refrigeration.
