Small area XPS at a spatial resolution of 30 mum has been used to study the heterogeneity of the fracture surface of a carbon fibre/epoxy composite with thermoplastic PEEK particles incorporated at the interlaminar boundary. Strong evidence was found for a chemical interaction between the PEEK particles and the matrix, in particular the curing agent. Careful charge compensation was required, particularly for the non-conducting PEEK particles alone which had been mounted on insulating adhesive tape, in order to produce a high quality spectrum. It was also observed that, for the fracture surfaces, the application of low energy electrons was successful in eliminating the differential charging observed during the simultaneous analysis of matrix and particle (insulating), or matrix and fibre (conducting).