The response of a reduction gas detector (RGD) to C2-C6 alkenes, C2-C6 alkanes, isoprene and benzene has been investigated using gas chromatography (GC) with a packed column. The RGD is considerably more sensitive to alkenes than is the flame ionization detector. The detection limit of this present GC/RGD system for alkenes is about 0.01 ng. It has much greater sensitivity to alkenes than to alkanes. Its sensitivity increases with increasing HgO bed temperature, but its selectivity towards alkenes decreases at the same time. The selectivity of the RGD may not be significant for much heavier molecules. The sensitivity of the RGD is inversely proportional to the carrier gas flow rate through the HgO bed. The baseline of the system increases significantly with increasing oven temperature.