Magnetization and neutron diffraction studies have been carried out on CeScSi-type Tb x Er 1− x Ti 0.85Mo 0.15Ge compounds (space group I4/ mmm, no. 139). These compounds demonstrate ferromagnetic collinear 1 (FC1), ferromagnetic collinear 2 (FC2) and ferromagnetic non-collinear 1 (FNC1) types of ordering. Below T FC1 = 131 K for Tb 0.25Er 0.75Ti 0.85Mo 0.15Ge and T FC1 = 194 K for Tb 0.5Er 0.5Ti 0.85Mo 0.15Ge the magnetic structure of these compounds consists of ferromagnetic (0 0 2) rare earth double layers with magnetic moments of rare earth atoms the [0, 0, M z ]. Below T FC2 = 242 K for Tb 0.75Er 0.25Ti 0.85Mo 0.15Ge and T FC2 = 280 K for TbTi 0.85Mo 0.15Ge the magnetic structure of these compounds consists of ferromagnetic (0 0 1) layers with magnetic moments of rare earth atoms the [ M x , 0, M z ]. Below T FNC1 = 63 K for ErTi 0.85Mo 0.15Ge, T FNC1 = 14 K for Tb 0.5Er 0.5Ti 0.85Mo 0.15Ge, T FNC1 = 29 K for Tb 0.25Er 0.75Ti 0.85Mo 0.15Ge and T FNC1 = 75 K for TbTi 0.85Mo 0.15Ge the magnetic structure of these compounds consists of ferromagnetic (0 0 2) layers, but the magnetic moments of R atoms in the neighbouring layers are non-collinear.