The optical properties of Tm 3+ in a fluorophosphate glass are reported. Oscillator strengths and Ω λ parameters for Tm 3+ were calculated. Energy transfer between Ce 3+ → Tm 3+, Tm 3+ → Eu 3+ and Tm 3+ → Tb 3+ were measured at room temperature and interpreted using the Yokota and Tanimoto scheme. Fluorescence decay results seem to support the hypothesis of a diffusion-limited relaxation. The effects of Tb 3+ and especially Ce 3+ on the fluorescence of Tm 3+ ion point out the interest of these dopants for obtaining a better emission of Tm 3+ at 450 nm.