AbstractRates of mass and heat transfer to single spheres and cylinders at low Reynolds numbers are predicted from boundary‐layer theory. The velocity distributions which are assumed to exist are those derived from the linearized Navier‐Stokes equations by Tomotika and Aoi.In the case of the sphere the Nusselt number is found to be a function only of the Peclet group when the Stokes streamline function is assumed to apply. Experimental data for mass and heat transfer to singel spheres fall 10 to 40% higher than predicted from the theory. Experimental data for heat and mass transfer to single cylinders at largeNPecheck the theory.Curves are also plotted for the efficiency of removal of colloidal particles by combined direct interception and diffusion for both spheres and cylind