The cross-flow microfiltration (CFM) of fruit juices allows obtaining products of high quality by conserving their organoleptic characteristics and microbiological stability during storage. The effect of the main macro-compounds and the transmembrane pressure (TMP) on the process performance with model fluids was evaluated. The model fluids concentration varied between 0.25 and 0.75% for pectin and 0.04 and 0.08% for cellulose. To study the influence of transmembrane pressure (TMP) and concentration on the hydrodynamic properties of the fouling layer (K, C.sub.g), diffusivity (D) and the boundary layer thickness (delta.sub.b) the Box-Behnken design with three replicas in the center was used. It was found that the CFM process is efficient and commercially feasible when working at a constant TMP of 1.93 bar and at concentrations of pectin and cellulose of 0.25% and 0.0513%, respectively.