AbstractThe effect of CuO addition on the phase composition of clinker and the Cu incorporation into the structure of clinker phases was monitored under laboratory conditions. Separate synthesized CuO‐doped clinker phases as well as clinkers with different CuO content up to 4 wt.% were characterized by XRD, optical and electron microscopy with EDS analysis. It has been found that Cu tends to form a separate phase or a double oxide with Ca and incorporates in the clinker phases to a limited extent, except for C4AF. With increasing CuO content in clinker, its phase composition changes, and the size of alite crystals increases.