Abstract. Earlier studies have demonstrated that soil texture and geochemistry strongly affect soil organic carbon (SOC) content. However, those findings primarily rely on data from temperate regions with soil mineralogy, weathering status and climatic conditions that generally differ from tropical and sub-tropical regions. We investigated soil properties and climate variables influencing SOC concentrations across sub-Saharan Africa. A total of 1,601 samples were analyzed, collected from two depths (0\u201320\u2009cm and 20\u201350\u2009cm) at 45 sentinel sites from 17 countries as part of the Africa Soil Information Service (AfSIS) project. The dataset spans climatic conditions from arid to humid and includes soils with a wide range of pHH20 values, weathering status, soil texture, exchangeable cations, extractable metals and a variety of important land cover types. The most important SOC predictors were identified by linear mixed effects models, regression trees and random forest models. Our results indicate that SOC is primarily controlled by aridity index (PET/MAP), exchangeable calcium (Caex) and oxalate-extractable aluminum (Alox); this was found across both depth intervals. Oxalate-extractable iron (Feox) emerged as the most important predictor for both depth intervals in the regression tree and random forest analyses. However, its influence on SOC concentrations was strong only below Feox concentrations of 0.25\u2009wt\u2009%. This suggests that Feox can act as a pedogenic threshold \u2013 even on a continental scale. Across model-ling approaches, clay and fine silt content (