A new approximate analytical method for studying mass and heat transfer problems is presented which makes it possible to obtain simple algebraic equations for diffusion (thermal) flows and mean Sherwood numbers. The problems are considered concerning convective mass transfer to a rotating disk, longitudinally streamlined plate, a spherical droplet, and a solid particle in the course of volumetric reaction the rate of which is arbitrarily dependent on concentration. Non-stationary mass exchange between a wall and a motionless medium with simultaneous volumetric reaction of any order is studied. Heat and mass transfer in a turbulent flow in the tube inlet section and other analogous problems are analysed.