In this paper, the structural characteristics of the modified celluloses from acacia pulp in Vietnam were investigated and compared to other pulps. The total crystalline index (TCI), the lateral order index (LOI) and the hydrogen bond intensity (HBI) were evaluated by the FTIR spectra. The size of crystallites was considered by XRD patterns. Peak separations were carried out using Gaussian deconvolution for the band at 3700 -3000 cm -1 of the FTIR spectra and the XRD spectra. The results show that the TCI, LOI and HBI of modified acacia cellulose I are found to be around 1.09, 2.22 and 2.33, respectively, and the TCI, LOI, HBI of acacia cellulose II are found to be around 1.09, 1.51, 2.06, respectively. The crystalline size of modified acacia cellulose I is found to be as follows L(101) ~ 4.33 nm, L(101 ) ~ 8.58 nm and L(002) ~ 4.80 nm, and that of cellulose II is found to be as follows: L(101) ~ 4.04 nm, L (101 ) ~ 3.55 nm and L(002) ~ 2.99 nm.