The physical properties of barbunia bean seed were determined as a function of moisture content in the range of 18.33-32.43% dry basis (d.b.). The average length, width and thickness were 16.68 mm, 9.36 mm and 7.51 mm, at a moisture content of 18.33% d.b., respectively. In the moisture range from 18.33% to 32.43% d.b., studies on rewetted barbunia bean seed showed that the thousand seed mass increased from 751.77 to 859.63 g, the projected area from 73.85 to 97.35 mm(2), the sphericity from 0.632 to 0.644, the porosity from 47.85% to 48.56% and the terminal velocity from 14.23 to 16.63 m s-1. The bulk density decreased from 639.24 to 579.29 kg M and the true density from 1225.68 to 1126.15 kg m(-3) with an increase in the moisture content range of 18.33-32.43% d.b. The static coefficient of friction of barbunia bean seed increased the linearly against surfaces of four structural materials, namely, rubber (0.213-0.271), aluminium (0.161-0.222), stainless steel (0.147-0.207) and galvanised iron (0.169-0.246) as the moisture content increased from 18.33% to 32.43% d.b. (c) 2006 Elsevier Ltd. All rights reserved.