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Land degradation resulting from soil erosion is a global concern, with the greatest risk in developing countries where food and land resources can be limited. The use of fallout radionuclides (FRNs) is a proven method for determining short and medium-term rates of soil erosion, to help improve our understanding of soil erosion processes. There has been limited use of these methods in tropical Africa due to the analytical challenges associated with 137 Cs, where inventories are an order of magnitude lower than in the Europe. This research aimed to demonstrate the usability of 239+240 Pu as a soil erosion tracer in western Kenya compared to conventional isotopes 210 Pb ex and 137 Cs through the determination of FRN depth profiles at reference sites. Across six reference sites 239+240 Pu showed the greatest potential, with the lowest coefficient of variation and the greatest peak-to-detection limit ratio of 640 compared to 5 and 1 for 210 Pb ex and 137 Cs respectively. Additionally, 239+240 Pu was the only radionuclide to meet the 'allowable error' threshold, demonstrating applicability to large scale studies in Western Kenya where the selection of suitable reference sites presents a significant challenge. The depth profile of 239+240 Pu followed a polynomial function, with the maximum areal activities found between depths 3 and 12 cm, where thereafter areal activities decreased exponentially. As a result, 239+240 Pu is presented as a robust tracer to evaluate soil erosion patterns and amounts in western Kenya, providing a powerful tool to inform and validate mitigation strategies with improved understanding of land degradation., Competing Interests: Declaration of competing interest There are no conflicts to declare., (Crown Copyright © 2023. Published by Elsevier Ltd. All rights reserved.)