Crude oil refineries in Indonesia produce waste in the vacuum distillation as vacuum residue and utilization is still low. Vacuum residue contains high aromatics which can be utilized as raw material to produce activated carbon. Such a activated carbon is widely used as electric double-layer capacitors. Vacuum residue was mixed with dehydrated castor oil as conjugated double bond source, then followed by pyrolysis at heating rate of 5°C/min until 450°C and holding time at 450°C for 90 minutes. The amount of dehydrated castor oil added to vacuum residue was varied at 0 wt%, 5wt%, 10 wt%, and 15 wt% of vacuum residue. Co-pyrolysis of vacuum residue and dehydrated castor oil reduce C/H atomic ratio precursors, from 1.82 to 1.50, 1.48, and 1.45 and used as a precursor of activated carbon. The activation was conducted by activating the precursor with KOH solution and followed by carbonization at heating rate of 5oC/min until 700oC and holding time at 700°C for 30 minutes. The results show that the addition of castor oil improved pore surface area from 150.32 m2/g to 236.97, 290.99, and 357.78 m°/g, respectively, and also have high crystallinity structures, so they may be used as active materials in capacitors.