Biogas is produced from anaerobic digestion of organic biodegradable materials. However, its application is limited as it contains impurities such as carbon dioxide (CO2), hydrogen sulphide (H2S), and other trace gases. Chemical absorption is capable of producing gas of high methane content above 95% and has no methane losses hence it's widely used on large scale applications. Sodium hydroxide was used for cleaning the biogas in this study at a concentration of 1 M, 2 M, and 3 M. The effect of concentration on absorption and CO2 removal efficiency was studied. It was observed that an increase in concentration lead to an increase in the absorption rate and the removal efficiency respectively. The highest removal efficiency was recorded to be 66%.