The structure, magnetic and magnetocaloric properties of the Ge-rich Gd 5 Ge 2.05–x Si 1.95–x Mn 2x (x=0.01 and 0.03) alloys were investigated by scanning electron microscopy, X-ray powder diffraction, differential scanning calorimeter (DSC) and magnetization measurements. The results of energy dispersive X-ray analysis (EDX) and X-ray diffraction analyses showed that the composition and crystal structure of the alloys were desired. DSC measurements were performed to determine the transformation temperatures for each alloy. Both alloys exhibited the first order phase transition around room temperature. The alloys showed an anti-ferromagnetic transition around 60 K. The isothermal magnetic entropy changes of the alloys were determined from the isothermal magnetization measurements by using the Maxwell relation. The maximum values of isothermal magnetic entropy change of the Gd 5 Ge 2.05–x Si 1.95–x Mn 2x alloy with x=0.01 was found to be −12.1 and −19.8 J/(kg·K) using Maxwell equation around 268 K in applied fields of 2 and 5 T, respectively.