We report on magnetization measurements on U(Ga1−xMx)2, M=Cu, Ge and Al, with 0⩽x⩽0.2. All studied samples are ferromagnetic and the magnetization at low field depends on the sample history. Substitution of Cu for Ga strongly shifts Tc to lower temperatures (79K for x=0.1) and induces the formation of a spin-glass phase above x=0.2. The Al- and Ge-doped samples present only a small reduction of Tc reaching 118K for x=0.1. Our results are not explained by the unit cell volume behavior, and indicate that the electronic configuration of the non-f element is responsible for the magnetic properties of this system. The observed reduction of the effective moment indicate that the Uranium moment becomes more delocalized for the Cu- and Ge-doped samples when compared to U(Ga,Al)2.