This thesis considers the feasibility of using the electromagnetic techniques to monitor the wear of the refractory base of a glass-making furnace. The research focuses in building a system that is able to provide measurements of the distance to the molten glass in this demanding high temperature application. The main challenge in this project is to eliminate the effect of the refractory supporting steel structure and still be able to detect and exploit a much smaller signal from the molten glass. In order to differentiate between the molten glass and the steel supports, a multi-coil, multi-frequency technique was proposed, studied and implemented in this research.