Biomass gasification process is considered a promising waste-to-energy conversion technique to eliminate the immense environmental issues accompanied with open field burning. The objective of this study is to experimentally study the dynamic behavior of an Imbert based design manufactured bench scale gasifier using cotton stalks as a feed stock. Air was employed as a gasifying agent with a biomass batch feed of 4 kg. The gasification process characteristics are evaluated in terms of lower heating value, gasification efficiency, and operation time. The applied air flow rates are (60, 100, 150, and 200 l/m) achieving varied equivalence ratios between 0.362 – 0.232. An optimum average lower heating value and cold gas efficiency of 4.34 MJ/m3 and 61.7 % respectively are attained at equivalence ratio, ER of 0.304.