Biomass is widely recognized as a sustainable resource for producing activated carbon for environmental applications and energy. However, the main disadvantage remains the production of activated carbon from biomass with a large surface area that can be effectively used for ecological treatment. The present study shows the effect of different activation methods to produce activated carbon from mango trees' wood residues. Pre-treatments for mango tree wood residues were done with carbonization at 400 ᵒC for 30 min. The produced was impregnated in KOH solution (1:1 ratio) for chemical activation. Afterward, the char created was dried at 105 ᵒC for 60 minutes in the oven. Four different diameters of 3, 4, 5, and 6 mm of produced char were achieved. Samples of 100 g from char were activated at four different temperature levels of 300, 350, 400 and 450 ᵒC for activation times of (15, 20, 25 and 30 min), respectively. The gage pressure of the atmosphere was recorded in the activation process at a constant nitrogen flow rate of 50cm³/min. The results showed an effect on the surface area of produced activated carbon. The best surface area for produced activated carbon was 1199.8m²/g at maximum methylene blue absorption of 528.9 mg/g, the temperature of 400 ᵒC, activation time of 30 min and under atmospheric pressure for the specimens of 3 mm in diameter.