Abstract:The cell-wall polysaccharide from Amorphophallus rivieri was found to be a mannan of MW. 72000. The anomeric configuration was determined from the specific rotation and IR spectrum of the polysaccharide. Smith degradation gave glycerol acetate only. The complete methylation followed by hydrolysis and acetylation gave 2,3,4,6-tetra-O-methyl-1, 5-di-acetylmannitol, 3,4,6-tri-O-methyl-l,2,5-tri-acetylmannitol and 3,6-di-O-methyl-l,2,4,5-tetra-acetylmannitol in the ratio of 1.08: 32: 1. Based on all of these results, the structure assigned to the repeating unit of the polysaccharide was given.