Single crystal of bismuth tellurite Bi 2 TeO 5 (BTO) doped with trivalent thulium (Tm 3+ ) was grown by the Czochralski method and investigated by spectroscopic techniques (absorption, emission). Absorption and emission of the Tm:BTO crystal collected in the VIS-IR spectral range are presented. Spectroscopic features were investigated as a function of the excitation light polarisation (E//X, Y, and Z axis of optical indicatrix) and sample temperature. The oscillator strength of the 3 H 6 → 3 F 4 transition at 1.7 µm was determined by numerical integration of the X, Y and Z polarised absorption spectra. The obtained values are: P X = 4.7 × 10 -6 , P Y = 6.8 × 10 -6 and P Z = 5.9 × 10 -6 that gives a mean value P mean = 5.8 × 10 -6 . Emission was observed from the 1 G 4 and 3 H 4 levels. The 3 H 4 and 1 G 4 excited state dynamics was studied. Decay curves and time constants of luminescence were collected at 5 and 300 K and analysed. The 3 F 4 → 3 H 6 luminescence at around 1.8 µm was too weak to be acquired from the low concentrated sample. However, based on optical data it was possible to estimate the radiative probability A rad of this transition and the 3 F 4 radiative lifetime. The resultant values are: A rad = 668 ± 0.4 s -1 and τ rad = 1.5 ms.