Computational fluid dynamics (CFD) is applied to the study of the catalytic hydrogenation of sunflower oil in the presence of a supercritical solvent. A 2D CFD model of a single Pd-based catalyst pellet is presented. Intra-particle concentration profiles for all species present in the mixture (oil fatty acids and hydrogen) are obtained and compared against experimental results. Different particle sizes are studied and external mass transfer and intra-particle diffusional effects are analyzed. External mass transfer coefficients are obtained and presented. Fitting of the intra-particle concentration profiles allowed to verify the kinetic reaction model. The verified kinetic reaction model and intra-particle diffusion coefficients were utilized in a 3D packed bed reactor model, and conversion profiles are obtained. (c) 2007 Elsevier Ltd. All rights reserved.