Effect of Sn addition on the mechanical and electrical properties of Cu–15%Cr in-situ composites has been studied. The addition of 0.1%Sn is effective for the solid solution hardening. Accumulation of high density of dislocations and development of banding structure by cold drawing give the increment of tensile strength. The precipitation of Cr in cupper matrix was accelerated and distinct secondary hardening occurs after cold rolling and aging treatment. It was found that the tensile strength of 1100 MPa with electrical conductivity of 70%IACS were attained in the Cu–15%Cr–0.1%Sn by the optimization of thermomechanical processing.