Two copper alloys containing different amounts of phosphorus, 6 and 80 wtppm, respectively, have been investigated. The matrix of both alloys was analysed using atom probe tomography (APT). The matrix P concentration in the 80 wtppm P mate- rial was about the same as the bulk concentration and it was therefore concluded that the majority of the P atoms resides in the matrix. Grain boundaries in the alloy con- taining 80 wtppm P were investigated using transmission electron microscopy and energy dispersive spectroscopy. No P could be detected, suggesting that the local grain boundary concentration should be below about 0.1 at%, or alternatively that the grain boundary coverage is smaller than 1/10th of a monolayer. The results in this study suggest that the mechanism by which P suppresses creep embrittlement is not related to strong GB segregation.