This papers present a 31P MAS NMR study of the binary P2O5/GeO2 glassy system. A structura model is proposed based on the identification of 3 main peaks : P-OH and Q2(I/II) sites (P-O-P and P-O-Ge). I think further NMR experiments are needed to support the structural model developed by the authors. They are standard experiments and it is curious that they have been performed and/or shown. First the peak assigned to POH suggests a uncontrolled hydration of the samples (how are the sample air-sensitive ?). It appears on all sample but not 30% and 45% GeO2. How a surface alteration and/or hydration can be excluded. I suggest a light thermal treatement to check this point (ATD/ATG/DSC analysis). What are the density of the samples ? Why no 1H MAS NMR performed (very simple...) and 1H/31P CPMAS NMR experiments (this also a standard NMR experiments). Yet the authors could push the NMR up to a 2D HETCOR MAP. In addition, 31P is a very sensitive nucleus so that DQMAS (31P-31P, Double Quantum) can be considered, to some extent, as a standard experiments (and for a publication in a NMR journal). These experiments could confort the interpretation of the Q2(I/II) peaks. Otherwise, the paper is not suitable for publication in MRC but for a journal oriented to materials. But In that case, I am afraid data are missing conerning the glass properties (density, check of composition, ...). Thus my conclusion is that this work must be enriched in NMR data or published elsewhere (but with more characterization of the samples analyzed).