Near‐infrared to visible upconversion characteristics of Er3+in CdX2‐based halide glasses (X=Cl, Br, or I) has been investigated. When4I9/2state is pumped by 800 nm radiation from an AlGaAs laser diode, the upconverted green emissions (520–560 nm) of2H11/2+4S3/2→I15/2transition are clearly observed in all the glasses. The linewidth of green emission in these glasses becomes narrow in the order of chloride, bromide, and iodide. The CdCl2and CdBr2system glasses give blue upconversion luminescence (around 410 nm) due to the2H9/2→I15/2transition, but this emission is not observed in the CdI2system glass because of the absorption edge at around 450 nm. The fluorescence spectra of CdX2system glasses suggest that the multiphonon relaxation rate depends on choice of theXspecies. ©1995 American Institute of Physics.