The manuscript entitled “Heterogeneous hybrid nanocomposite based on chitosan/magnesia hybrid films: Ecofriendly and recyclable solid catalysts for organic reactions” deals with the synthesis, characterization and use of a heterogeneous catalysts. Introduction seems adequate, and balanced in references cited. Characterization of catalyst is adequate. Discussion needs some improvement (see below). Through the text, when one sees (Cs-Mg), it is difficult not to consider Cs as cesium metal, instead of chitosan. Perhaps, for sake of clarity, the authors could change it to CHI, or CHIT. I know sometimes CS also appears, but when “joined” with Mg, it gets confusing. At least use CS instead of Cs (capital letters). Figures must be presented in a manner that text is of the same size as inline text. Definition should be improved as well. What’s the use of presenting a table and not discussing it? Table 1 shows solvent comparison (not catalyst). What is the opinion of the authors on the results? Polar protic or aprotic, what is the best solvent and why? What is the main difference between this and many other known reusable catalysts for this reactions? A comparison with literature would be important. Again, in table 2 (and table 3), does not compare catalysts (there is only one), but only solvents. Once again, why were these solvents chosen? Despite not being absolutely novel (the approach), the manuscript may be accepted, once improvements are made.