Physical properties of kernels, grains, and seeds are necessary for the design of equipment to handle, transport, process and store the crop. The physical properties of popcorn kernels have been evaluated as a function of kernel moisture content, varying from 8.95% to 17.12% (db). In the moisture range, kernel length, width, thickness, arithmetic mean diameter, and geometric mean diameter increased linearly from 8.18 to 9.14 mm, 5.71 to 6.32 mm, 3.65 to 4.90 mm, 5.85 to 6.79 mm and 5.54 to 6.55 mm respectively with increase in moisture content from 8.95% to 17.12%. The sphericity, kernel volume, kernel surface area, and thousand seed weight increased linearly from 0.677 to 0.717, 73.24 to 125.14 mm(3), 96.26 to 134.92 mm(2), and 136 to 157 g, respectively. The true density and bulk density decreased linearly from 1.304 to 1.224 g/cm(3) and 0.771 to 0.703 g/cm(3) respectively while porosity increased from 40.87% to 42.56%. The highest static coefficient of friction was found on the plywood surface. The static coefficient of friction increased from 0.55 to 0.74, 0.47 to 0.62, and 0.46 to 0.61 for plywood, galvanized iron, and aluminium surfaces respectively. The angle of repose increased linearly from 25.3 degrees to 30.8 degrees with the increase of moisture content. (c) 2004 Elsevier Ltd. All rights reserved.