Screening of transition metal complexes typically involves elaborative experiments in batch reactors in organic solvents under non-steady-state conditions. In contrast, screening of immobilized catalysts in a fixed-bed continuous gas-phase reactor enables highly efficient and precise investigations on activity and stability under steady-state. In this work we present a technique to immobilize numerous homogeneous transition metal complexes (Ru, Ir, Os, Fe, Cu, Mo, Pd Re, Rh) in the ionic liquid [BMMIM][OTf] on the highly porous support Silica 100 using the Supported Ionic Liquid Phase (SILP) technology. All prepared SILP catalysts were investigated in the water–gas shift reaction (WGSR) in a continuously operated fixed-bed reactor at temperatures between 120 and 160°C and ambient pressure. Best activities and stabilities were found for ruthenium-based systems.