This study aims to determine the process synthesis parameter for a concurrent activation and surface modification (CAM) process to produce activated carbon (AC) from palm kernel shell (PKS). It is targeted to obtain high impregnation of metal functionalized group on the AC for adsorption of acid gas. The process uses sulphuric acid (H2SO4) and barium chloride (BaCl2) as activating agent and surface modification agent. The impregnated barium amount in AC was determined by inductively coupled plasma-optical emission spectrometry (ICP-OES) and X-ray fluorescence (XRF). This study utilized a batch process under different acid mass loading and activation temperatures. The ICP-OES analysis results showed that AC treated with 10 % H2SO4 at various activation temperatures (400-700 °C) exhibited high impregnated barium amounts ranging from 1.24 to 2.98 wt%. The XRF analysis also shows high impregnated barium amount ranging from 27.44-35.46 wt% for AC prepared at similar conditions. This manifests that lower acid mass loading ascribed to lower barium sulphate (BaSO4) formation after surface modification with BaCl2, which then facilitates porous structure development in PKS derived AC (PKSdAC) and sintering of barium metal on its surface during CAM by preventing sealing of pores by unreacted BaSO4 and barium sulphide (BaS) after washing of AC.