Abstract The diffusive motion of Li + ions has been investigated in lithium silicophosphate glasses between 300 K and the glass transition temperature by means of 7Li and 31P nuclear spin relaxation and electrical conductivity experiments. The data are analyzed in terms of the coupling model. The effects of the mobile cation concentration and of the nature of the network atoms on the ionic transport properties have been determined. The results are interpreted in view of various theoretical approaches. Moreover, we are able to observe an additional fast relaxation process which is related to local rearrangements of the network atoms (β-process). As this process is only detected by nuclear spin relaxation and not by conductivity, we conclude that the underlying mechanism is caused by local rearrangements of uncharged [PO 4] 0 tetrahedra belonging to the glassy network.