High carbon content-activated carbon with high micro-porosity was prepared from thin walnut shell by pyrolysis process with chemical activation (using KOH), exhibiting the promising potential to be a very good adsorbent. The aim of the study was to evaluate the effect of activation temperature, holding time and impregnation ratio on moisture content, total carbon content, ash content, BET surface area, adsorption capacity, total pore volume and iodine absorption value. Design expert predicted 5500 C activation temperature, 2.5 h holding time and 1:1 impregnation ratio as optimum conditions for development of activated carbon. The developed activated carbon was compared with market sample activated carbon for physico-chemical properties and surface characteristics. The developed activated carbon was characterized by high carbon content (80.06 %), BET surface area (735.36 m2/g), iodine absorption value (783.64 mg/g), adsorption capacity (201.31 mg/g), low ash content (5.01 %) and total pore volume (0.29). XRD patterns of activated carbon developed from thin walnut shell confirmed its highly amorphous structure. FTIR analysis indicated similarities in peaks at different wave numbers with no significant differences in both samples. SEM-EDX analysis revealed highly porous structure with high carbon, potassium elemental composition of developed activated carbon as compared to market sample.