Magnetic and magnetocaloric properties of cubic Laves phase RCoNi (R Gd, Tb, Dy, and Ho) compounds have been studied. The RCoNi (R Gd, Tb, Dy, and Ho) compounds order ferromagnetically at ∼200 K, ∼113 K, ∼68 K, and ∼42 K (TC), respectively. Field dependent magnetization data of RCoNi at 5 K in fields up to 7 T reveal saturation behaviour with minimal hysteresis. Magnetocaloric effect in terms of isothermal magnetic entropy change has been calculated. Maximum isothermal magnetic entropy change values of ∼-7.2 J/kg/K, ∼-10.1 J/kg/K, ∼-15.5 J/kg/K, and ∼-19.6 J/kg/K are obtained for RCoNi (R Gd, Tb, Dy, and Ho) compounds for 7 T field change close to TC. Substitution of 50 at. Ni in Co-site of RCo2 has led to the reduction of TC of the parent compounds by nearly one-half, but broadened the magnetic entropy change vs T curve and hence improved the relative cooling power. The large magnetocaloric effect associated with RCoNi compounds makes them potential candidates for low temperature magnetic refrigeration applications. © 2013 American Institute of Physics.