The rate of evaporation from a water droplet suspended by a glass capillary in a wide range of vapour pressure was measured. Moreover, the method of sweat evaporation from a porous sphere was used as a supplemental experiment, in which the Reynolds number was up to about 1.63 × 103. Care was taken to cool the glass suspender by evaporation cooling and to ensure constant temperature of the droplet during the measurement. Subsequently, the following conclusions are arrived. 1. The heat transfer coefficient was not affected by the vapour concentration and N.u = 2 + 0.63 Pr1/3 Re1/2. 2. The mass transfer coefficient should be described as a function of vapour concentration and Sh(PBM/P)n = 2 + 0.63 Sc1/3 Re1/2 where n = ‐ (0.4 ‐ 1/Sc1/3 Re1/2).