The surface tension of oxide melts is difficult to measure. Even for binary slags with a low degree of polymerisation such as calcia-alumina, there seems no benchmark value for the surface tension available. Published data exhibit considerable scatter even for similar compositions which prevents to build a reliable and consistent database of frequently used physical properties. This study presents an attempt to use three different measurement techniques in the same hightemperature furnace to obtain the surface tension of a binary calcia-alumina slag close to eutectic composition, namely the drop weight method, the pendant drop method, and, for the first time, the oscillating jet method (for circular and elliptic jets) as a function of temperature. The methods used in the present context are explained, and the experimental results evaluated with respect to previously published data. A consistent and coherent trend is observed when the drop weight and the oscillating jet methods are compared.