The Mesoproterozoic domain of the Rehoboth Basement Inlier (RBI) in central Namibia is composed of sedimentary and volcanic rocks which have been intruded by coeval granites of batholithic dimension as well as numerous quartz-feldspar porphyries and mafic dykes. Review of the geochemical, petrographical and geochronological data in combination with field observations and the analysis of high-resolution geophysical magnetic and radiometric data suggests Mesoproterozoic evolution of this area in three stages. The development of a first basin is recorded by clastic fluvial and limnic sedimentary rocks of the Billstein formation with only minor if any felsic pyroclastic activity.