An optical investigation of the properties of europium (II) ions introduced in Ba2Mg3F10 single crystals is presented. The spectra and time-dependence of both the inter-configurational (f–d) and the intra-configurational (f–f) transitions are described. The emission spectrum consists of two emitting Eu2+ centres, each showing one broad f–d band and one 6P7/2 quartet. The thermal equilibrium between the f–f and f–d emitting states is investigated and found to take place on a microsecond timescale for one of the two Eu2+ centres. The spectroscopic results combined with numerical modelling of the influence of the host crystal on the 6P7/2 energy scheme allow the assignment of each f–f and f–d emission to its corresponding Eu2+ centre.