Treatment of used frying oil with natural adsorbents from palm oil fuel ash (POFA) could improve its quality. Fresh palm oil fuel ash (FPOFA) and burned palm oil fuel ash (BPOFA) are higher effective to reduce FFA than synthetic adsorbents (celite and silica gel). BPOFA improved viscosity and colour of used frying oil also synthesis adsorbents. The results shown that the palm oil fuel ash can be used to improve the quality of used frying oil instead of commercial synthetic adsorbents.