A field experiment was carried out at the main block of Tarnak Farm of Afghanistan National Agricultural Sci- ences and Technology University, Kandahar during the summer season of 2015, to determine the effects of differ- ent potassium fertilizer levels on yield and economics of hybrid maize (Zea mays L.). The experiment consisted seven potash application treatments of 30, 60, 90, 120, 150, 180, 210 kg K O/ha and a control in a randomized 2 complete block design (RCBD) and replicated thrice. Grain and stover yields were significantly affected by 90 kg K O/ha which were at par up to 210 kg K O/ha. Significantly higher net returns (108.6 103 Afghani/ha) and ben- 2 2 efit: cost ratio (1.16) were observed by the application of 180 and 60 kg K O/ha, respectively. However, a dose of 2 157.7 kg K O/ha was found as economic optimum dose for growing maize in semi-arid condition in Kandahar 2 province of Afghanistan.