The Central Rift in Kenya (CRK) comprises the lakes Naivasha, Elementaita and Nakuru and the Longonot, Eburru and Menengai volcanos. The alkaline magmas, produced by the volcanoes within the CRK, lead to solid rocks likes trachytes, phonolites, and fewer basalts and accompanied soft rocks like ashes, tuffs, pumices and ignimbrites (e.g. Macdonald et al., 1987; Macdonald, 2014). Lacustrine sediments and beds of diatoms are remnants of former lake level variations caused by climate variability and topographic changes (e.g. Stoof-Leichsenring et al., 2011). The samples have been taken within the frame of a VW-Foundation funded project that tries to detect, map and monitor groundwater pollution from anthropogenic and natural sources. For a previous VW-Foundation funded project (grant 85465), also the groundwater fluoride enrichment in the CRK have been studied (Olaka et al., 2016).This data report presents the metadata, inclusive GPS data from 52 solid volcanic rock and sediment samples taken during a field excursion during May 2017. A geological map with all data locations is included in this report. After sample preparation, we performed X-ray diffraction (XRD) analyses to get the mineral content and X-ray fluorescence (XRF) as well as Ion-Chromatographic (IC) analyses to get the elemental concentration of those samples. The results are given together with analytical limitations and few additional information despite a graphic visualization of the XRD-data.The data are presented in tab-delimited text format and described in the dataset description.