Manual cono weeding in rice is a tedious job requiring more labour and energy. An effort was made to develop prototype of a self propelled cono-weeder under the AICRP on Weed Management at the College of Horticulture, Kerala Agricultural University, Vellanikkara, Thrissur with an objective to reduce drudgery involved in manual cono-weeding in rice. Main components of the newly developed self propelled cono-weeder are the main frame, a prime mover, front and rear floats and a rotor. Field experiment was conducted at Pattambi in Palakkad district to study the performance of the prototype in comparison with manual cono weeding and conventional weeding methods in rice. The weed density, weed dry weight and the grain and straw yields of rice at various treatments were observed. It was found that self propelled cono-weeder had a field capacity of 0.1 ha/h at an operating speed of 2.0-3.0 km/h. The weeding efficiency of the unit in rice was at par with that of the manual cono-weeder operated twice at 15 and 30 days after transplanting.