Understanding the mechanisms that controlthe filtration of a complex fluid like skimmedmilk is a major challenge in the development ofmembrane-based processes in the dairy indus-try. One of the main limiting factors for thedevelopment of membrane separation processeslies in the formation of irreversible deposits nearthe separating membrane, which needs a chemi-cal cleaning to be reversed. An irreversiblestructure of casein micelles deposit have alreadybeen shown to be responsible for low perme-ation fluxes and soluble protein transmissions,leading to minimum productivity and separationin crossflow microfiltration (0.1mm) of skimmedmilk [1]. However few studies have reported therelationships between the characteristics andproperties of the deposits and physico-chemicaland hydrodynamic parameters of the filtrationoperation. This work is intended to study the characteris-tics of accumulated matter (reversibility, irrevers-ibility, specific resistance, thickness, mass) undervarious operating conditions (transmembranepressure, duration, pH, ionic strength, ion nature)at 48–50°C, which is a current temperature usedin the dairy industry. The aim is to investigate theoperating conditions under which irreversibledeposit is limited. The deposit properties are explained takinginto account the characteristics of the caseinmicelles (size, zeta potential, hydration), whichare the main components of the fouling layersformed at the membrane surface.