Data shows the composition (in wt. %) and the modelled temperature-viscosity relationship (800-1600 degrees) for various generic compositions of magmas and variable water contents. These data are used for the viscosity curves shown in figure 11 of Kendrick and Lavallée, 2022 (https://doi.org/10.2138/rmg.2022.87.20). The data involve only idealised compositions, not real samples, and the data was compiled at the University of Liverpool, UK. These data were compiled in 2021. The generic magma compositions were input into the open access Viscosity calculator "GRD", available at; https://www.eoas.ubc.ca/~krussell/VISCOSITY/grdViscosity.html and the resulting temperature-viscosity relationship for each generic composition was generated, providing the lines used in Fig. 11 of the review paper Kendrick and Lavallée, 2022. These data help understanding the viscosity-temperature relationship of different composition magmas with different dissolved water content.