The low-temperature viscosities of dry and hydrous X (X=Li, Na, K, Ca0.5, Mg0.5)AlSi3O8 melts have been investigated. The samples were hydrated via piston cylinder synthesis, and the water contents were subsequently determined by Karl-Fischer titration (KFT) and IR spectroscopy. Both the anhydrous and hydrous viscosities were measured using the micropenetration technique in the range of viscosities between 108.5 to 1011.9 Pa s, at 1 atm pressure and in the temperature ranges of 745–990°C and 400–790°C for the dry and wet melts, respectively. The range of water content varied for all of the samples from 0.70 to 3.13 wt.% H2O. The viscosities of dry melts vary, at fixed temperature, as a complex function of the identity of the cation in the order Li