This study aims to determine the characteristics of oil palm boiler ash (OPBA) after processing with ball mill and coprecipitation methods. The method used is OPBA from a palm oil mill, processed using a ball mill for 1 hour at a speed of 250 rpm. Then prepared with the coprecipitation method by dissolving it in 2M HCl solution and NaOH solution with variations (2; 2.5; 3) M. Particles were characterized by XRD, SEM, XRF, and FTIR. XRD characterization shows the size of each crystal (83,79; 72,30 and 56,31) nm, with trigonal crystal structure with the SiO2 phase. SEM shows a homogeneous mixture. EDX shows the biggest elements are Si, O and C content. XRF shows the amount of silica is 31.45%. FTIR shows absorption peaks which are the characters of molecular vibrations of the sample.