Abstract A heavy metal oxide borate glass with composition (70− x)PbO–18B 2O 3–6Al 2O 3–3WO 3 (wt%) was modified by variable content of PbF 2 ( x = 9 , 36 and 72 wt%) and doped with 1 wt% of Pr 3+ or Tm 3+ ions. The influence of the PbF 2 content on optical properties and luminescence dynamics has been observed through the variation of an effective line width of 1D 2→ 3H 4 and 1G 4→ 3F 4 emissions as well as the 1D 2 and 1G 4 lifetimes of Pr 3+ and Tm 3+, respectively. It was observed that the increase of PbF 2 content leads to narrowing of the 1D 2→ 3H 4 band from 680 to 590 cm −1. This effect was not observed for the 1G 4→ 3F 4 thulium emission. The variation of luminescence kinetics was observed both for Pr 3+- and Tm 3+-doped samples; the increase of the PbF 2 content has changed the 1D 2 lifetime from 13.8 to 16.5 μs and from 34 to 43 μs for the 1G 4 level.