The water-gas shift reaction (WGS) was evaluated in two Pd–Ag membrane reactors operating in parallel and capable of processing 0.25 Nm3·h−1 of syngas. Various configurations, syngas compositions, and steam flow rates were explored within the temperature range of 300–350 °C and pressure range of 4–8bar. The performances were evaluated in a coupled configuration, consisting of a permeator and a membrane reactor operating in series, and single configuration of membrane reactor. Two syngas mixtures were fed and treated under different combinations of temperature, pressure, and steam/CO ratio. The syngas composition used was, in one case that typically produced by updraft gasifiers operated with air and having a content of H2 19.1 vol% and, in the second case, having content of 36.8 vol%, typically achievable by oxy-steam gasification. Carbon monoxide conversion, hydrogen permeation, and hydrogen permeability of membranes were determined. The use of these membranes effectively enhances the WGS reaction, overcoming the performances of a Gibbs reactor, and produces streams of ultrapure hydrogen. Competitive strong adsorption of CO was suggested from the permeability analysis and comparison with existing literature.