A new tetragonal Gd 11 Ge 8 In 2 phase has been obtained by arc-melting and annealing at 800 °C. The structure has been determined and refined from single crystal X-ray diffraction data in the I4/mmm space group with a = 11.2091(6) and c = 16.3994(9) Å. Phases with the RE 11 Ge 8 In 2 (RE = Gd–Tm) composition were subsequently synthesized and their structures were refined using X-ray powder diffraction methods. Magnetic measurements carried out on RE 11 Ge 8 In 2 (RE = Gd–Tm) indicated a ferromagnetic ordering in all phases. The magnetocaloric effect in terms of the magnetic entropy change, ΔS mag , was evaluated for the Gd-, Tb- and Tm-containing samples, and the largest |ΔS mag | value of 10.6 J/kg K was obtained for Tm 11 Ge 8 In 2 .