AbstractIn order to find out the correct size required for heat exchangers, waste‐heat boilers, gas coolers, etc., heat‐transfer coefficients are needed. Although the available literature provides us with the most recent formulae for these coefficients it is nevertheless difficult to assemble all the technical data of the required dimensions. This is especially tedious for those who deal only occasionally with the subject.The physical and chemical properties of the gases are given partly in British and partly in metric units. Thus the inevitable conversion needed to reduce all the figures to the one system of measurement requires much time and study if mistakes are to be avoided. Furthermore, the values given for the thermal conductivity of gases differ in a remarkable degree in the various available lists which, also, ignore many of the more recent valuable experimental figures.The writer has therefore prepared charts for the rapid determination of heat‐transfer coefficients and the presentation of new data based on recent experimental figures for the thermal conductivity of single gases and of gaseous mixtures. These charts are applicable to the gases commonly used in industry.