The primary excited state decay and energy transfer processes in singly Tm 3-doped TeO 2:ZnO:Bi 2O 3:GeO 2 (TZBG) glass relating to the 3F 4 → 3H 6 ∼1.85 m laser transition have been investigated in detail using time-resolved fluorescence spectroscopy. Selective laser excitation of the 3H 4 manifold at 794 nm, the 3H 5 manifold at 1220 nm, and 3F 4 manifold at 1760 nm has established that the 3H 5 manifold is entirely quenched by multiphonon relaxation in tellurite glass. The luminescence from the 3H 4 manifold with an emission peak at 1465 nm suffers strong suppression due to cross relaxation that populates the 3F 4 level with a near quadratic dependence on the Tm 3 concentration. The 3F 4 lifetime becomes longer as the Tm 3 concentration increases due to energy migration and decreases to 2.92 ms when Tm 3 4 mol. as a result of quasi-resonant energy transfer to free OH - radicals present in the glass at concentrations between 1 10 18 cm -3 and 2 10 18 cm -3. Judd-Ofelt theory in conjunction with absorption measurements were used to obtain the radiative lifetimes and branching ratios of the energy levels located below 25 000 cm -1. The spectroscopic parameters, the cross relaxation and Tm 3( 3F 4) → OH - energy transfer rates were used in a numerical model for laser transitions emitting at 2335 nm and 1865 nm.