Abstract The surface tension, density, and viscosity of the Ni-based superalloy CMSX-4� have been determined in the temperature ranges of 1,650–1,850 K, 1,650–1,950 K, and 1,623–1,800 K, respectively. Each property has been measured in parallel by different techniques at different participating laboratories, and the results are compared with the aim to improve the reliability of data and to identify recommended values. The following relationships have been proposed: density-ρ (T) [kg� m−3] = 7,876 − 1.23(T − 1,654 K); surface tension-γ (T) [mN�m−1] = 1,773 − 0.56 (T − 1, 654 K); viscosity-η (T) [mPa�s] = 8.36 − 1.82 � 10−2(T − 1,654 K). For a comparison, surface-tension measurements on the Al-88.6 at% Ni liquid alloy with the same Al-content as the CMSX-4� alloy were also performed. In addition, the surface tension and density have been theoretically evaluated by different models, and subsequently compared with new experimental data as well as with those reported in the literature. The surface-tension experimental data for the liquid CMSX-4� alloy were found to be close to that of the Al-88.6 at% Ni alloy which is consistent with results from the compound formation model (CFM). [ABSTRACT FROM AUTHOR]