Distillation at total reflux of binary mixtures was carried out in a disc column to find the effect of transport properties of fluids and flow rates on the mass transfer coefficients. The apparatus employed was a disc column consisting of nineteen stainless steel discs 0.5732 in. diameter × 0.1674 in. thick. These were threaded edgewise on a vertical stud at right angles to each other, and housed centrally in a 1.0 in. diameter × 12 in. long glass tube. The five binary mixtures chosen represented a wide range of chemical species and physical properties.