The present work is related to the development of predictive methods for fretting wear which incorporate the effects of fretting wear debris. During the fretting process, debris is produced and accumulated within the contact region, reducing metallic contact between the contacting bodies. This paper describes the successful application of a nano-indentation technique to measure the mechanical characteristics of the debris layer and the alloy immediately below the debris layer, as produced from cylinder-on-flat fretting wear tests on Ti-6Al-4V. The test programme involved testing at different normal loads, strokes and numbers of cycles, to capture the evolution of the debris layer geometry, as well as the mechanical characteristics. Post-test examination of the fretting scars through the cross-section using optical and scanning electron microscopy suggests that the debris exists as an oxidised compacted layer structure. A scanning electron microscopy technique was developed to characterise the evolution of debris layer thickness distribution with numbers of cycles. (C) 2009 Elsevier B.V. All rights reserved.