The ageing behaviour of a Cu-15 wt% Cr in-situ composite was investigated systematically by means of hardness testing, electrical conductivity measurement, scanning electron microscopy, analytical transmission electron microscopy and high-resolution electron microscopy. The material was found to have a peak hardness after ageing at around 773 K and a peak electrical conductivity at around 873 K. In contrast with the dilute Cu-Cr alloys, Cr-rich clusters were observed at the early aged condition in the Cu matrix, which matches not only the results of mechanical and physical property measurement but also the theoretical prediction. In addition, the precipitates at peak hardened condition in the Cu matrix were determined to be Cr Guinier-Preston zones. Cr ribbon as the in-situ reinforcing element shows no measurable ageing effect due to the high-temperature solution treatment.