Caseins obtained by high speed centrifugation was used as study material and different pH solutions were prepared. Zeta potential, conductance, viscosity, average particle size and stability were studied. The result showed that Zeta potential value (absolute value), conductance value and viscosity value increased gradually with pH increase. The average particle size first decreased and then increased by PH and had the minimal size at 26.03nm with pH6.2 . Solutions with the pH between 5.8 and 6.6 were more s...