Slag properties, such as electrical conductivity, thermal conductivity, density, viscosity, and surface tension, and the prediction of these properties play an important role in melting and metal refining. Optical basicity depends on the electronegativity of the ions of an individual oxide. This feature represents the bonding characteristics, ionization ability, ion size, and consequently the mobility of free ions inside the slag. These properties affect the electrical conductivity of slags. Therefore, in the current study, various slags containing mainly CaF2 and various oxides were prepared. The optical basicity value of each slag was calculated and their electrical conductivities were measured between 1450A degrees C and 1600A degrees C. The relationship between the optical basicity and the measured properties were discussed. It was observed that increasing optical basicity increases the electrical conductivity as well as the temperature. Thus, a new model for predicting electrical conductivity of slags was built between 1450A degrees C and 1600A degrees C depending on optical basicity and temperature.