One of the most common rare-earth doped luminescent nanoparticles (RE-LNPs) for remote temperature sensing areis based on fluoride hosts co-doped with Yb3+ (as sensitizer) and Er3+ (as an activator). The Yb3+ sensitizer ions are efficient absorbers of 980 nm infrared radiation via its unique 2F7/2 → 2F5/2 electronic transition and so they can transfer this energy to the Er3+ ions, and, thus, RE-LNPs can emit visible, ultraviolet and eventually infrared radiation (at wavelengths below 980 nm) under 980 nm excitation. Although the 980 nm wavelength excitation lies in the biological window (650-1800 nm) and thus presents a high penetration depth into tissues, it is strongly absorbed by water, which can cause a substantial overheating in cells and tissues. To address this problem, it is imperative to shift the excitation of RE-LNPs co-doped with Yb3+ and Er3+ to a more appropriate wavelength without deteriorating their emission efficiency and thermal sensibility. In this study, as an alternative, they were fabricated via co-precipitation method Yb3+/Er3+-doped calcium fluoride (CaF2) nanoparticles (~ 21 nm), with different concentration of Er3+ (ranging from 0.5 to 4 mol%), to act as a luminescent nanothermometer under 1064 nm CW diode laser excitation. The ability of temperature sensing of Yb3+/Er3+ co-doped CaF2 luminescent nanoparticles was investigated under anti-stokes excitation. The highest relative thermal sensitivity was found to be 2,09% K-1. As the excitation (1064 nm) and emission (660 nm) lie into within the spectral regions (650-1350 nm) where tissues become partially the photothermal the damage in biological tissues can be avoided/minimized. Finally, we report their potential application for real-time thermal sensing.