A new flow-through reaction cell consisting of an X-ray transparent semicrystalline thermoplastic has been developed for percolation experiments. Core holder, tubing and all confining parts are designed of PEEK (polyetheretherketone) to allow concomitant surveillance of the reaction progress by X-ray microtomography. The reaction progress of the flow-through experiment can be monitored without dismantling the sample from the core holder.