Magnetic properties of orthorhombic RCoSn (R = Tb-Er) and RRhGe . (R =
Ce,Nd) (of the TiNiSi-type of crystal structure), were studied by mag
netometric and neutron diffraction methods. All RTX compounds order an
tiferromagnetically at low temperatures. The magnetic structure of TbC
oSn and HoCoSn is sine-wave-modulated with the wave vectors k1 = (0, 0
.25, 0.11) and k2 = (0, 0.333, 0), respectively. The magnetic structur
es of CeRhGe and NdRhGe compounds are collinear (C mode). Magnetic mom
ents of 1.4(2) and 2.0(2) mu(B) localized respectively on Ce and Nd io
ns, are aligned along the a-axis.