The present publication documents the findings of geological mapping project of an area of about 9000~km$^{2}$ between 2° 00'W and the Ivory Coast border from 7°30' to 8°30'N. This studied area consists of Proterozoic rocks: Birimian sediments and volcanics and Tarkwaian sediments, which are folded and metamorphosed and intruded by Eburnean granitoids (2145-2090 Ma). The Bui Belt, the dominant structural feature, crosses the area from NE to SW. In the middle of the belt there is a Tarkwaian basin, over 100 km long and up to 17 km wide, containing gold-bearing heavy minerals. In addition to the mapping, a basin study as well as geochemical and geophysical investigations were carried out to evaluate the gold potential of the Tarkwaian. The first paper ``Geology of the Bui Belt Area in Ghana'' are the Explanatory Notes to the Geological Map of Ghana 1:100,000, sheet 0703 A (Sampa), sheet 0703 B (Wench)) and sheet 0803 D (Banda). It describes all individual rock units on the geological maps and refers to noteworthy geological features on individual sheets. The results of the basin study are presented in the second paper ``Sedimentation and Structure in the Tarkwaian Group of the Bui Basin in West Ghana''. The results of the geophysical investigations (magnetics, radiometry and gravimetry) in the central part of the Bui Belt are given in the third paper ``Geophysical Investigation in the Bui Belt in West Ghana''. The fourth paper ``Mineral Occurrences, Geochemical Investigation and Gold Potential in the Bui Belt Area in West Ghana'' deals with the results of the geochemical research on sediment and hard-rock samples from the Bui Belt Tarkwaian, as well as on hard-rock samples from Birimian. An estimate of the gold potential of the Tarkwaian of the Bui Belt is made in this paper. The volume presents the results of geological research performed during a joint Technical Cooperation Project in Western Ghana, involving the Geological Survey Department (GSD), Accra, and the Federal Institute for Geosciences and Natural Resources (BGR), Hannover.