An environmentally friendly method was developed to remove HCl from industrial waste gases, specifically the gas produced from a catalytic reforming process. The method uses activated-carbon-supported NaOH (NaOH/C) to treat the HCl-containing gas. A continuous-upflow fixed-bed reactor was used to test the performance of the prepared NaOH/C. Because chlorides contained in the off-gas stream of a reformer are normally less than 100 ppm, the cycle length of the NaOH/C will be expected to reach 1 year, and an accelerated aging test with a HCl concentration of 223 000 ppm was developed to shorten the test time. The accelerated aging test was confirmed to be reliable because the HCl treatment capacity of the NaOH/C for the accelerated aging test is almost the same as (within 15% deviation) that for standard tests with a gas stream containing 1000 ppm HCl. Effects of the water content on the performance of the NaOH/C were investigated by the accelerated aging test, and the results indicated that the HCl treatment capacity of the NaOH/C increases with increasing water content of the NaOH/C up to 27% and then slightly decreases. NaCl formed by the neutralization of HCl in the gas with NaOH on NaOH/C was removed by flowing low-pressure steam, and the activity of NaOH/C was rejuvenated by resoaking the activated carbon with a NaOH solution. Thus, the activated carbon of NaOH/C can be reused repeatedly. In addition, the HCl treatment capacity of the NaOH/C is about 6 times that of commercial alumina, normally used in the reformer. The developed method lends itself to industrial application.