MEMBRAPOR’s durable sensors allow accurate measurements also in harsh conditions. Recently, a hydrogen compensated CO sensor for very high concentrations was introduced. The CO/SF-10000-4E-S allows the measurement of CO from 0 till 1% with H2 concentrations in the same magnitude. It is based on the well-established 4-electrode setup as it is known from the CO/CF-2000-4E. The signal compensation of the interfering hydrogen enables accurate monitoring of carbon monoxide in flue gas cleaning systems.