Continuously rising demands to steel products increase the necessity of applying special melting techniques like electro-slag remelting (ESR). This process is mainly characterised by the remelting slag which influences not only the product's cleanliness but also the energy consumption of the ESR process. Consequently, the electric conductivity of the slag is gaining in importance. Nonetheless, the metallurgic features of the slag with regard to steel cleanliness improvement must not deteriorate with varying conductivities. The present work outlines the influence of electrode quality and slag on steel cleanliness and energy consumption. The examined steel was a X38 CrMoV 5-1 which was remelted in an open ESR process. In order the characterise the electric conductivity, standard slags with defined amounts of additives were analysed with an electric conductivity measuring unit at the Chair of the Metallurgy at the University of Leoben. Since the electric and chemical properties of the slags possibly change during remelting, they were tested before and after the remelting process. Additionally, the pool of the remelted blocks was analysed to show a potential influence of varying slag compositions on the solidification structure.