Here we present a systematic investigation of the upconversion spectral properties of Er3+ doped in LaPO4, BaZrO3, Y2O3 and Yb3+/Er3+ doped in Gd2O2S, La2O2S, Y2O2S and this report was written as a comment to the article `Structural and NIR to Visible Upconversion Properties of Er3+-doped LaPO4 Phosphors` by Kesavalu et al.in J. Luminescence, 171 (2016) 51–57. According to the results published in this article Er3+doped LaPO4 was considered as the brightest in comparison with the rest of the phosphors which is scientifically not acceptable in terms of the material properties and we conclude that this experiment was not executed properly. Our results show that the metal oxysulphide based hosts M2O2S (M = Y, Gd, La) doped with Yb/Er are the brightest in comparison with the rest of the phosphors and our results also support the fact that the phonon energy of M2O2S is the lowest among these phosphors.