The physical and static bending properties of cultivated `rotan manau` (Calamus manan) reacted with acetic anhydride at 110 °C for the time intervals of 0.25 to 30 hours were investigated. The study aimed to investigate the effects of various reaction times on the physical and static bending properties. Rattans aged 10 and 13 years were obtained from local rubber tree plantations. This study found that almost all the physical properties of acetylated rattan were not significantly different by age (except specific gravity changes) and reaction periods (except weight gain and OH substitution). The static bending properties varied by rattan age, which the modulus of rupture (MoR), modulus of elasticity (MoE) and maximum load (ML), was not significantly different by reaction period for both ages, except for the MoR of the older acetylated rattan. The acetylation of rattan, performed at 110°C for prolong reaction period, did not impair the static bending properties.