In this study, rice husks (RHs), an agriculture by‐product, were used as precursor for the production of activated carbon by chemical activation with ZnCl2‐CuCl2 composite activator. The effect of process variables, such as ZnCl2 concentration, CuCl2 concentration, activation temperature, and activation time, were investigated. The optimal process condition was obtained through orthogonal test. Then the morphology, pore structure, and surface chemistry of rice husk‐based activated carbon (RAC) were analyzed. When using 5 mol/L ZnCl2 and 0.4 mol/L CuCl2 at the carbonization temperature of 500°C for 1.5 h, the BET surface area of the produced activated carbon was as high as 1924 m2/g and the total pole volume reached 1.493 cm3/g. The surface area was strongly affected by ZnCl2 concentration and the subsequent activation temperature. RAC prepared under the optimum conditions had remarkable adsorptive properties and notable treatment effect for fuchsine. © 2015 American Institute of Chemical Engineers Environ Prog, 35: 133–140, 2016