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Upconversion luminescence of Er^(3 )/Yb^(3 )-doped halide tellurite glass is investigated experimentally upon 976-nm excitation. Three intense emissions centered at 525, 545 and 655 nm owing to the transitions (2)^H_(11/2) → (4)^I_(15/2), (4)^S_(3/2) → (4)^I_(15/2) and (4)^F_(9/2) → (4)^I_(15/2), respectively, are observed when pumping power is as low as 20 mW. The upconversion mechanisms and power dependent intensities are discussed. The high-populated (4)^I_(11/2) level is supposed to serve as the intermediate state responsible for the upconversion processes.