We analyze the suitability of Nd3+doped phosphate glasses as optical temperature sensors based onthe response of their luminescence bands to temperature. At room temperature, laser excitation of thesample at 532 nm results in an emission spectrum with an intense band centered at 880 nm and anadjacent weak broad band centered at 810 nm, corresponding to the Nd3+ion transitions:4F3/2→4I9/2and4F5/2→4I9/2respectively. Because of thermalization effects between the next4F3/2and4F5/2energylevels (E ≈ 908 cm−1), a detectable change on the relative intensities of these emission bands occurswhen temperature is increased, affording the experimental calibration of the fluorescence intensity ratiowith temperature in the range 300–850 K. It has been shown that the radiative transfer processes favoredby the content of Nd3+ions are also responsible for changes to the spectra shapes and so play an importantrole in the fluorescence intensity ratio. A reliable thermal sensing operation was obtained in a 0.1 mol%doped Nd3+phosphate glass with relative sensitivity values ranging from 153 × 10−4K−1at 300 K to22 × 10−4K−1for 850 K, demonstrating good prospects for optical temperature measurements comparedto other reported results. However, the reabsorption measurements seen in the samples with a higherNd3+content reveal that the reliability of the sensing performance is compromised with the dopingconcentration and the experimental conditions of the measurement.