Cooking oil as foodstuffs that people necessary daily, both industry and households. The high price of cooking oil encourages people to use it repeatedly. The use of used cooking oil continuously can decrease the intrinsic value of the oil and toxic. One method to enhance the quality of used cooking oil is adsorption. The effort to regenerate used cooking oil for sustainability, adsorbents from environment materials are used to adsorb components in used cooking oil in order to raise the standard of cooking oil after purification and can be processed into other products such as biodiesel. Result by this study, the effect of mass and size of the adsorbent on the contact time was observed to reduce the turbidity of used cooking oil. The adsorption process was carried out on used cooking oil with a volume of 100 ml and variations in the mass of the adsorbent from corn cobs were 2 g, 3 g, and 4 g. The size of the adsorbent was varied at 50 mesh, 70 mesh and 100 mesh. The analysis carried out are measuring turbidity of used cooking oil using a Turbidity meter, SEM-EDX and determining the adsorption kinetics model.