Chlorophyll has long been considered to have health benefits and is widely used as a food additive. The conventional extraction method using organic solvents involves penetration and diffusion through many layers of a leaf structure, making it hard to predict and control. A diffusion equation with boundary conditions based on the wetting theory was proposed. Three kinds of solvent-acetone ethanol, and dimethyl sulfoxide - were used to extract chlorophyll from creeping oxalis. Chlorophyll of three kinds of plants (creeping oxalis, nodalflower synedrella, and broomjute sida) were extracted by 80% acetone. The amounts of extracted chlorophyll were in good agreement with the theoretical prediction. The effective diffusion coefficient of the chlorophyll transport increases with increasing energy barrier of chlorophyll wetting at the epidermis for all solvent types, acetone concentrations, and plant species. The barrier height of chlorophyll wetting increases with surface energy of plants. (C) 2013 Elsevier Ltd. All rights reserved.