High-pressure single crystal X-ray diffraction studies of a natural chondrodite, Mg_4.76Fe_0.22Ti_0.02Si_1.99O₈(OH_1.26F_0.74), and a synthetic OH-chondrodite, Mg_4.98Si_2.01H_2.00O₁₀, were performed using a diamond anvil cell (DAC) up to 7.3 and 5.9 GPa, respectively and at room temperature. FT-IR spectra of the natural chondrodite under high-pressure conditions up to 9.9 GPa was also observed using a DAC. The axial linear compressibilities of these samples are calculated as β_a = 1.69(4) × 10⁻³, β_b = 2.98(4) × 10⁻³ and β_c = 2.74(5) × 10⁻³ (GPa⁻¹) for the natural chondrodite and β_a = 2.11(18) × 10⁻³, β_b = 2.83(18) × 10⁻³ and β_c = 3.04(38) × 10⁻³ (GPa⁻¹) for the synthetic OH-chondrodite. The isothermal bulk moduli of these samples were calculated as K_T = 124.1(4) GPa for the natural chondrodite and K_T = 117(2) GPa for the OH-chondrodite, by using the Birch-Murnaghan equation of state assuming K' = 4. The bulk moduli of total void space in each sample, assuming K' = 4, were calculated to be K_⌊ = 116(2) GPa for the natural chondrodite and K_⌊ = 113(4) GPa for the OH-chondrodite. The plots of bulk modulus versus the summation of the filling-factor of polyhedral sites show a good correlation between the humite minerals. This relationship can be explained by the replacement of 4O²⁻ + Si⁴⁺ ⇔ 4(F, OH)⁻ + ⌊ generated in the humite homologous series. In the FT-IR spectra of the natural chondrodite, four OH-stretching vibrational peaks were observed at 3688, 3566, 3558 and 3383 cm⁻¹ under ambient conditions. The pressure dependences of the frequency of these peaks up to 9.9 GPa are 2.8(3), 3.9(3), 4.0(3) and −2.1(2) (cm⁻¹GPa⁻¹), respectively. With increasing pressure up to 9.9 GPa, the 3383 cm⁻¹ peak shifts to lower-frequency positions, whereas the other peaks shift to higher-frequency positions. The shortening of the O5···O5 distance, which is not the shared edge between M3 octahedra, related to hydrogen bonding with increasing pressure causes the negative pressure-dependence of the 3383 cm⁻¹ peak. The positive pressure-dependence of the remaining IR-peaks is due to the compression of the O5-H bond, and not related to hydrogen bonding with increasing pressure.