Abstract A series of Dy(Co 1− X M X ) 2 (M=Al Si, Ga, Ge) compounds has been prepared by arc melting method. The X-ray diffraction analysis reveals that all samples are in the MgCu 2-type structure. After the substitution, the Curie temperature increases remarkably. A first-order phase transition changes into a second-order one with increasing X. The magnetic entropy changes as a function of the temperature in a magnetic field of 1 T for Dy(Co 1− X M X ) 2 has been calculated. The origin of the large magnetic entropy change and the potential application of Dy(Co 1− X M X ) 2 as a working material for magnetic refrigerants have been discussed.