This paper presents an experimental and theoretical study of the liquid-to-wall mass transfer in a packed bed reactor with single phase liquid flow. The measurements were carried out by means of the classical electrodiffusion method and the influence of Schmidt number was particularly investigated A model based on the division of the packed bed into a core zone and a wall zone was developed. Each zone has different but constant porosity, superficial velocity and lateral dispersion coefficient. By simply assuming that the lateral dispersion coefficients are equal to the diffusion coefficient, the model predicts correctly the experimental results.