The spectroscopic properties of rare earth ions in many different hosts have been investigated, including surveys of Nd<sup>3+</sup> in silicate, phosphate, fluorophosphates and fluoride glasses. Some of the thermal-optical properties of materials are influenced by temperature change, such as thermal diffusivity, specific heat and luminescence quantum efficiency. In this work the luminescence quantum efficiency of PANK: Nd<sup>3+</sup>, as a function of temperature (80- 480 K), was investigated using the normalized lifetime thermal lens technique. This system presents high quantum efficiency at low Nd<sup>3+</sup> concentration and at ambient temperature, ~100%, which decrease as temperature increase. Below room temperature the effects are not in accord with the maximum value of η, which must be unity.