Single-crystal structure determinations at room temperature and elevated temperatures were carried out on the silver ion conductor Ag5Te2Cl, and the hitherto unknown structure of the room-temperature phase (beta-Ag5Te2Cl) was determined. Ion pathways are discussed for the room- and high-temperature phase by analyzing the joint probability density functions. Main transport pathways at different temperatures were worked out to obtain detailed insight into the movement of the silver atoms in this material. Ag5Te2Cl is an excellent 1D ionic conductor having a pronounced silver mobility along complex silver columns. Conductivities are sigma = 1.51 x 10(-3) Omega(-1) cm(-1) at 323 K and sigma = 4.30 x 10(-1) Omega(-1) cm(-1) at 469 K. With use of a nonharmonic description of the silver distribution of the high-temperature phase, a promising structure model has been derived for the room-temperature phase. beta-Ag5Te2Cl can be regarded as an intermediate phase between the disordered high- and the ordered low-temperature phase, showing an almost ordered silver distribution in addition to a slightly different arrangement of the anionic substructure.