Two new oxalate-bridged Gd(III) coordination polymers, namely, (choline)[Gd(C2O4)(H2O)(3)Cl]Cl center dot H2O (1) and [Gd(C2O4)(H2O)(3)Cl] (2), were first obtained ionothermally by using a deep eutectic solvent (DES). The magnetic studies and heat capacity measurements reveal that the two-dimensional Gd(III) based coordination polymer of 2 has the higher magnetic density and exhibits a larger cryogenic magnetocaloric effect (MCE) (Delta S-m = 48 J kg(-1) K-1 for Delta H = 7 T at 2.2 K).