Groundnut (Arachihy pogaea Linn.) is an important oil seed in India which accounts for around 25% of the total oilseed production of the country. Shelling can be generally done manually or using small machineries. Hand or manual shelling is labour intensive, another means of shelling is use of hand operated semi cylindrical type of machine and using power (motor/engine) operated high capacity type of ground nut decorticators. New machine is considered, which is operated by 0.5 hp. electric motor having main shaft, decorticating cylinder, blower. Standard test code IS 11473 was used which gives output capacity as 31.73 kg/hr and 32.552 kg/hr for the feed rates 40 kg/hr with decorticating efficiency 96.50 %, and 96.68 % with cleaning efficiency 83.45 % and 88.75 % respectively for Phule Pragati and Chitra varieties at fabrication estimation of Rs. 9959 approximately.