The fouling of cooling surfaces of industrial crystallizers is a major problem which reduces the productivity of installations. This phenomenon is initiated by primary heterogeneous nucleation at the wall, followed by growth,leading to the formation of a crystalline layer which increases the thermal resistance of the system. An experimental device was designed to study the conditions of appearance and subsequent growth of the layer. The influence of the main parameters was studied. Thermal modelling of fouling in an annular exchanger was performed, using the experimental results. This led to an evolution of the thickness of the layer with time and position. It also enabled the supersaturation profile to be calculated at any time, thus making the link between the growth of the layer and the kinetics of crystallization in suspension. Although a simplifying hypothesis was used for modelling, good agreement was obtained concerning the initial mass flow of crystallization, using growth rates obtained in suspension crystallization to calculate the growth in thickness of the layer.