Rubber seed shells are the wastes of rubber plants containing active compounds in the form of lignin, so that this part is quite potential to be processed into activated carbon products. Activated carbon is a material that contains amorphous carbon which has an internal surface that has a high adsorption capacity and is often used as an adsorbent. This study aims to determine the effect of the size of the adsorbent, the adsorbent dose and the modified adsorbent from rubber shells on the adsorption process of BOD, COD and TSS in tofu wastewater. Batch experimental adsorption using magnetic stirrer with a speed of 100 rpm during 8 hours, pHe of 7,5±0.2 and room temperature showed the optimum dosage adsorbent were 10 g/L, 355 microns particle size, resulting in decrease in the concentration and levels of BOD parameters from 1,300 mg/L to 109 mg/L and 91.61% percentage removal; COD parameters from 8,287 mg/L to 504 mg/L and 93.92% percentage removal; and TSS from 382 mg/L to 95 mg/L and 75.13% percentage removal, respectively. Therefore, the adsorbent from rubber seed shells has a potential to be used as an adsorbent for water and wastewater treatment. Keywords: activated carbon, adsorption, rubber seed shells, tofu wastewater