A model has been developed that correlates the anode temperature profile with the dynamic melting rate in gas metal arc welding. The components of this model are the electrode melting rate, the temperature dependent resistivity of the electrode, and the arc voltage. The differential equations describing the dynamic behaviour of the electrode extension were derived from the mass continuity and energy relations. The temperature of the electrode extension was determined by analysing conductive heat transfer and Joule heating effects. One-dimensional solutions for the temperature and heat content were used to obtain the dynamic melting rate equation. The purpose of the present paper is to provide quantitative analyses, concentrating on the thermal behaviour and the electrical characteristics of the arc welding system, to aid in achieving a fundamental understanding of the process, and to develop a dynamic model that can be used in adaptive control. The model is tested by comparison with experimental results.