The interaction between metallurgical coke and slag is an important aspect of furnace operation in both lead production and ironmaking. This interaction occurs in the dripping zone of the blast furnace, where molten phases trickle through a bed of metallurgical coke. The impact on productivity is significant, as the majority of PbO reduction takes place in this zone of the lead blast furnace, and the reduction of FeO to Fe occurs in this zone of the iron blast furnace. The relative importance of direct and indirect reduction reactions in the dripping zone are not yet fully understood. The conditions of this zone are hard also to replicate in a laboratory experiment. In this work, a literature review on the conditions of the lead blast furnace and on the reduction kinetics of slags with metallurgical coke is included. Current studies on coke-slag interactions are performed either by sessile drop experiments or by submersion of coke into a molten slag. Using the sessile drop technique, the mechanism for direct reduction of oxides in a slag phase with solid carbonaceous material was found to be one of two gas-ferrying mechanisms for the case of FeO reduction. For PbO reduction, a gas-ferrying mechanism or a series of electrochemical reactions can be active. The different mechanisms are simultaneously operating, but the dominating mechanism depends on the wetting behaviour of the slag-carbon couple. Using the submersion technique, mass transfer was found to be rate determining for low lead or iron oxide activities, whereas for higher activities, the chemical reaction becomes rate limiting. These test methods have their merit when discussing bath smelting reactors or the hearth of the blast furnace, but both of these techniques are insufficient to represent the dripping zone of the furnace accurately. A new, dynamic, method of testing is therefore proposed.