Experiments were carried out using a developed threshing machine with two rubber cylindrical drums to study the effect of drum clearance ( 2, 2.5, 3 and 3.5 mm ) and relative peripheral drum speed ( 1.1, 2.2, 3.3 and 4.4 m / sec ) on Black Seed properties, seed losses and threshing efficiency. And also, determination of power requirement and cost of Black Seed threshing. The test results indicated a maximum of 99.68 % threshing efficiency and 91.92 % cleaning efficiency, a minimum of 0.97 % total seed losses and a maximum germination of 87.8 %. The average output capacity of machine was 88.61 kg / h of seed and 19.90 kW.h / ton minimum power requirement. Producing one ton of Black Seed grain, using threshing machine costs about 752  L.E The performance was found to be influenced by all the study variables.