Kefir is a fermented beverage that has the ability of probiotics, often used as a cosmetic or ointment raw material because it contains lactic acid which is classified as AHA (Alpha Hidroxy Acid) which is good for the skin. The objectives of the present study were to get the optimum value of lactic acid, pH and viscosity; a study was conducted on the effect of temperature, incubation time and storage time on kefir goat and cow milk for 28 days. Testing of lactic acid value was calculated based on total acid value using the titration method, pH testing using a pH meter and viscosity using Brookfield viscometer. The results showed that the average value of lactic acid in kefir fermented for 48 hours at room temperature and incubator were 0.9-2.2%, pH value 4.1-4.3 and viscosity 1400-1600 cPs. While value of kefir lactic acid in stored for 24 days at room temperature and cold was 1.97- 3.54%, pH values 3.5-4.5 and viscosity 3400-10600 cPs. The optimal average yield of goat milk kefir is obtained on days 4-12 and can be stored for 24 days.