AbstractIn this work, a biodegradable fiberboard was prepared from modified bleached bamboo fibers. Cationic guar gum (CGG) was deposited onto the fibers, and the corresponding changes in physical properties of the composite were determined. Bleached bamboo fiber was modified by depositing cationic guar gum (CGG) onto the fibers. The treated fibers were then used to prepare biodegradable fiberboard. A 56.21% increase in tensile strength and a 54.40% increase in strain were obtained with the addition of 1.5 wt% of CGG. The bamboo fiber treated with CGG exhibited better thermal stability than the pure bamboo fiber. The surface morphologies of the unmodified and modified samples were analyzed using atomic force microscopy (AFM) in the tapping mode and scanning electron microscopy (SEM), which revealed differences in the fine structure of fibers, showing coarser surfaces spread across the fibers.