This paper presents an investigation of substance transport in an aqueous solution-gel system. In gels, free convection is damped and hydrodynamic instabilities do not occur, so it is possible to determine the influence of gravity on substance transport. With the aid of a laser interferometric method, specific experiments were performed under conditions in which the substance diffuses according to and against the gravitational force. The concentration profiles and the substance flows were calculated on the basis of interference image analysis. Comparison of the results indicates a noticeable influence of gravitational field on passive substance transport. The gravitational field significantly modifies the amount of transported substance and affects the concentration profiles as well as the time evolution of the concentration field. (C) 2010 Elsevier B.V. All rights reserved.