Abstract Spectroscopic properties of Pr 3+-doped selenide glasses and optical fibers were investigated for their mid-infrared applications in the spectral range of 3.5–5.5 μm. Optimal concentration of Pr 3+ was decided, and sensitizers for improved spontaneous emission of Pr 3+: ( 3F 2, 3H 6), 3H 5→ 3H 4 transition were examined. Spectral deconvolution analysis with corrected emission bands revealed effective interaction of the excited energy states. Optical fibers doped with Pr 3+ were fabricated and their spectroscopic properties were measured. Pumping scheme and energy transfer mechanism of the selenide fiber were investigated and discussed for its practical use.