Fluorescence lifetime sensing is useful to measure temperature in harsh environments. We implemented the technique using samarium doped materials. The sample was exposed to a pulsed laser beam and the resulting lifetime was measured. A plot of lifetime versus temperature exhibited a linear dependence. A small change in temperature produced a significant change in lifetime, which is important in measuring temperature accurately. This technique is an alternative when conventional techniques are not suitable.© (2006) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.