High temperature behavior of three compacted graphite iron (CGI) alloys on polycrystalline alumina substrates (99.7%, poro­sity <3%) were examined by the sessile drop method combined with classical contact heating procedure in flowing Ar. High-speed high-resolution CCD camera was used for continuous recording of the CGI/Al2O3 couples during melting alloy, heating to and holding the couples at the test temperature of 1450°C for 15 min and their subsequent cooling. The comparative studies were made with conventional CGI (in wt.%: 3.70 C, 2.30 Si, 0.44 Mn, 0.054 P, 0.017 Mg, 0.015 S) and two alloys additionally containing the same amounts of 0.25 Mo, 0.1 V, 0.045 Sn and 0.032 Sb with different concentrations of Mg + Cu additions, i.e. 0.01Mg + 0.33Cu and 0.02Mg + 0.83Cu. All three CGI alloys demonstrated non-wetting behavior on the Al2O3 substrates while the contact angle values slightly decreased with increase of the Mg + Cu content in the alloy, i.e. 131° (unalloyed CGI), 130° (0.01Mg + 0.33Cu) and 125° (0.02Mg + 0.83Cu). Structural characterization of solidified couples by light microscopy and scanning electron microscopy coupled with energy dispersive X-ray spectroscopy revealed: 1) heterogeneous nucleation of discontinuous graphite layer at the drop-side interfaces and on the surface of the drops; 2) reactively formed Mg-rich oxide layer at the substrate-side interface; 3) the formation of satellite droplets on the surface of the drops during their solidification; 4) degeneration of initially compacted graphite to lamellar graphite after remelting and subsequent solidification of the drops, particularly in their surface layer.