[en] Temperature investigation of infrared-to-visible frequency upconversion in erbium-doped tellurite glasses excited by CW laser radiation at 1540 nm and under cryogenic temperatures is reported. Intense upconversion emission signals around 530, 550 and 660 nm corresponding to the ²H_11/2, ⁴S_3/2, and ⁴F_9/2 transitions to the ⁴I_15/2 ground state were generated and studied as a function of the laser intensity and temperature. The upconversion excitation mechanism of the Er³⁺ ions emitting energy levels was accomplished via stepwise multiphoton absorption. The green upconversion luminescence exhibited a fivefold intensity enhancement when the temperature of the sample was varied in the range between 5 and 300 K. A maximum green upconversion intensity was attained around 120 K and a steady decreasing behavior for higher temperatures up to 300 K was observed. A model based upon conventional rate equations was used to model the observed temperature evolution of the upconversion luminescence