Magnetic properties and magnetocaloric effects of the R 6 Co 2 Si 3 compounds with R=Nd and Tb have been investigated by magnetization measurement. The Curie temperature and the saturation moment at 5K for R 6 Co 2 Si 3 with R=Nd and Tb are determined to be 84.5 and 186.9K, and 11.3 and 39.5μ B , respectively. The magnetic entropy change ΔS m of R 6 Co 2 Si 3 with R=Nd and Tb, which originates from a reversible second-order magnetic transition around T C , are obtained to be respectively 5.3 and 6.8J/(kgK) for a magnetic field change from 0 to 5T. A high refrigerant capacity for Tb 6 Co 2 Si 3 is found to be 441J/kg for a field change of 0–5T, which is due to a broad distribution of the ΔS m peak.