Soap made from waste cooking oil can be a potential product that can be developed to improve the economy and as an effort to preserve the environment by utilizing household waste. Waste cooking oil can be reprocessed into soap-based ingredients through an oil purification system so that the color is clear and does not smell rancid by using bagasse and orange peel adsorbents in the bleaching process. This service aims to train students' understanding of Mambaul Hikam Islamic boarding school about processing solid and liquid soap from waste cooking oil through the cold process method and the hot process method. The results of the service show firstly, the transfer of knowledge, skills, and affection for making liquid and solid soap using cold and hot process techniques through appropriate technology. Second, the formation of a community of students who can become facilitators in assisting the manufacture of laundry soap from used cooking oil waste. Soap production from this assistance is still an internal use of the Islamic boarding school but the students are expected to be able to increase the production of soap which can improve the economy of the santri and the Mambaul Hikam Islamic boarding school.