Abstract Ba2Mg(BO3)2 – Ba2Ca(BO3)2 solid-solution doped with Eu3+ has been synthesized by the conventional solid-state reaction. The symmetry is lower for Ba2Ca(BO3)2 (monoclinic) than Ba2Mg(BO3)2 (trigonal). The solid-solution has been prepared by substituting Mg2+ ions in Ba2Mg(BO3)2 (BaMBO) with larger Ca2+ ions in the whole percentage range. Eu3+ enters both Ba and Mg/Ca sites. As a result, the emission spectra and luminescent decay times differ under excitation at 395 nm, and 266 nm and the charge transfer band (CTB) energy is different for luminescence with a maximum at 594 and 616 nm (the 5D0 → 7F1 and 5D0 → 7F2 transition, respectively). Increasing Ca2+ concentration redshifts the higher-lying CTB, while simultaneously blue shifts the lower-lying CTB. For the Ba2Ca(BO3)2 the electric dipole to magnetic dipole ratio of the components of the 5D0 emission is smaller, and the luminescence decay time is longer than for the Ba2Mg(BO3)2 host. The Judd-Ofelt analysis shows that the Ωλ parameters do not change with Ca2+ concentration for Eu3+ at Mg/Ca site while changing significantly for Eu3+ at Ba site.