Abstract The luminescence of several trivalent ions (Gd3+, Dy3+, Tb3+, Eu3+, Ce3+ and Bi3+) in Ca4GdO(BO3)3 is reported. Many of these show high luminescence efficiency. Under 254 nm excitation Tb3+ and Eu3+ show a high light output. In this host lattice rapid energy migration through linear Gd3+ chains occurs. The O(1) ions in the host lattice which are not bonded to boron shift the energy levels of the luminescent ions to relatively low values owing to the high covalency. The Ce3+ ion does not luminesce in this host. This is ascribed to photoionization. The luminescence properties of activated Ca4Gd(BO3)3 are more similar to those of the activated oxides than to those of other activated borates. This is explained on comparison of the crystal structures.