The paper reports reference values of the viscosity of twelve gases (H2, CH4, CO, C2H4, C2H6, O2, CO2, C3H8, C4H10, SO2, CF4, SF6) at 25°C obtained in an oscillating-disc viscometer. As measured by long-range reproducibility, the precision is ±0.04 %, whereas the accuracy is estimated to be ±0.1 %. The paper also lists linear temperature corrections for viscosity at 25°C with an uncertainly of ±2.5 %.