North Bihar is a major producer of makhana [Euryale ferox], the main indigenous aquatic cash crop of Mithila (India). A prototype Makhana popping machine was developed to address the basic constraints and drudgery involved in Makhana processing, increase the processing capacity, minimize processing time, remove the drudgery of the operations involved as well as to improve the quality of popped makhana. The machine could have two units: a preheater-cum-roaster unit and an Impacter unit for popping. The popped makhana and the shell were collected from the discharge outlet of the makhana popping machine and separated. The yield of makhana, popping efficiency and recovery of grade I makhana were determined. The effect of impeller speed on grade-I makhana was negligible. The performance of the newly developed makhana popping machine was found satisfactory at 15 kg/h feed rate and impeller speed of 2650 rpm. The yield of popped makhana varies from 34.3 to 53.0% on raw seed (w.b.). A profit of Rs. 9.25 per kg is obtained by using this machine.