The Effect of Activated Carbon Variations on TiO2/MONMORILLORITE (MMT) Composites in Biodiesel Production from Cooking Oil Waste has been carried out. Diesel fuel in this decade can be reduced in use with biodiesel. In particular, Indonesia is a producer of vegetable oil from palm oil which is converted into biodiesel. Hydrocarbon and sulfur emissions can be reduced by using biodiesel, making it more environmentally friendly. In this research, TiO2/MMT/Activated Carbon catalyst composite material was used. Solid state method is used for the synthesis of the composite material. TiO2 and MMT materials were composited with a ratio of 25:75 wt%. Activated carbon is produced from palm oil bunches waste by carbonization process and chemical activation. Furthermore, the activated carbon was composited with a TiO2/MMT catalyst with various weight percent ratios of 10:90 wt% and 20:80 wt%. The composite material is a heterogeneous catalyst material. Each variation of activated carbon in the catalyst composite TiO2/MMT/C as much as 2 g is used in the transesterification process for biodiesel production. The process uses a reaction temperature of 62 °C for 3 h. The ratio of the molar ratio used is 1:12 between waste palm oil and methanol. The GC–MS results showed that there was a conversion of biodiesel from used cooking oil, namely 66.12% on the TiO2/MMT/C-10 composite catalyst. The biodiesel efficiency is still below the quality limit of the Indonesian National Standard (SNI), which is 96.50%.