A new equation of state has been derived for liquid uranium monocarbide by an application of the Significant Structure Theory of liquids which accounts for seventeen different “gas-like” molecules. Critical parameters have been calculated together with various thermodynamic quantities such as the vapour pressure, the saturated entropy, the isobaric thermal expansion, the isothermal compressibility, the standard free energy function and heat content. A graphical representation of the relationship between internal energy and pressure is also reported. In order to obtain a self consistent set of input data, a critical assessment of literature data for UC n ( n = 1−6) molecules was made. New thermal functions of these molecules as well as of neutral and first ionized uranium were calculated and are given together with the reevaluated atomization energies.